JPH11247690A - Fuel injection amount control device of multi-cylinder internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To judge whether or not the mean fuel injection rate of a first group of cylinders is equal to that of a second group of cylinders. SOLUTION: The cylinders of a multi-cylinder internal combustion engine are grouped into a first group and a second group, and an O2 sensor 13 senses the air-fuel ratio of the exhaust gas which is exhausted from the two groups of cylinders and converged, and when the obtained air-fuel ratio is equal to the theoretical value, the fuel injecting time of the first group is increased by a certain rate while the fuel injecting time of the second group is decreased by an amount obtained through multiplying the mentioned rte by [the number of first group cylinders/the number of second group cylinders], and if the air-fuel ratio after the process appears lean, judgement is passed that the mean fuel injection rate of the first group is smaller than that of the second group.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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

[0002]

2. Description of the Related Art Conventionally, there has been known a fuel injection amount control device for a multi-cylinder internal combustion engine having a plurality of cylinders of the same type provided with a fuel injection device of the same type for the purpose of improving the output of the internal combustion engine. ing. This type of fuel injection amount control device for a multi-cylinder internal combustion engine regards the fuel injection amount (hereinafter referred to as “fuel injection rate”) injected into a cylinder per unit time for each cylinder as equal to each other, and The fuel injection amount is controlled by controlling the fuel injection time.

[0003]

However, even with the same type of fuel injection device, due to the manufacturing error of the injection hole area of the fuel injection valve, the solenoid in the fuel injection valve, and the deterioration of the fuel passage over time, etc. It is possible that the fuel injection rate for each cylinder is different from each other. In such a case, if the fuel injection rate control is performed on the assumption that the fuel injection rates of the respective cylinders are equal to each other as in a conventional fuel injection quantity control device for a multi-cylinder internal combustion engine, good combustion can be performed in a certain cylinder. Even if it does, combustion will deteriorate in other cylinders.

In view of the above problems, the present invention determines whether or not the fuel injection rate of one cylinder is equal to the fuel injection rate of another cylinder, thereby reducing the variation in fuel injection rate between cylinders. An object of the present invention is to provide a fuel injection amount control device for a multi-cylinder internal combustion engine that can prevent the accompanying deterioration of combustion.

[0005]

According to the first aspect of the present invention, a cylinder is divided into a first cylinder group and a second cylinder group, and the first cylinder group and the second cylinder are divided. Air-fuel ratio detection means for detecting the air-fuel ratio of the exhaust gas that has been discharged and merged from the group, and when the air-fuel ratio of the merged exhaust gas is the stoichiometric air-fuel ratio, the fuel injection time of the first cylinder group is reduced by a fixed ratio. The fuel injection time of the second cylinder group is decreased by the fixed ratio × (the number of cylinders of the first cylinder group / the number of cylinders of the second cylinder group) together with the increase, or the fuel injection time of the first cylinder group is decreased. Increasing or decreasing the fuel injection time by a certain ratio and increasing the fuel injection time of the second cylinder group by the certain ratio × (the number of cylinders of the first cylinder group / the number of cylinders of the second cylinder group) Means and air-fuel of the exhaust gas joined after the operation of the fuel injection time increasing / decreasing means. A fuel injection system for a multi-cylinder internal combustion engine, comprising: a determination unit configured to determine whether an average fuel injection rate of the first cylinder group is equal to an average fuel injection rate of the second cylinder group based on the ratio. A quantity control device is provided.

According to a first aspect of the present invention, there is provided a fuel injection amount control apparatus for a multi-cylinder internal combustion engine, wherein the average fuel injection rate of the first cylinder group, that is, the total fuel injection amount of the first cylinder group is determined by the first cylinder group. The value obtained by dividing the number of cylinders by the fuel injection time and the average fuel injection rate of the second cylinder group, that is, the total fuel injection amount of the second cylinder group, by the number of cylinders of the second cylinder group and the fuel injection time It can be determined whether or not the value divided by is equal. Here, the number of cylinders of the first and second cylinder groups can be one or more arbitrary numbers. That is, when the first cylinder group is constituted by one cylinder, it can be determined whether or not the fuel injection rate of that cylinder is equal to the average fuel injection rate of the second cylinder group.

According to the second aspect of the present invention, the fuel injection time increasing / decreasing means increases the fuel injection time of the first cylinder group by a fixed ratio and sets the fuel injection time of the second cylinder group. When the air-fuel ratio of the exhaust gas joined after reducing the fuel injection time by the fixed ratio × (the number of cylinders of the first cylinder group / the number of cylinders of the second cylinder group) is lean, the first cylinder The fuel injection amount control device for a multi-cylinder internal combustion engine according to claim 1, wherein it is determined that the average fuel injection rate of the group is smaller than the average fuel injection rate of the second cylinder group.

According to a second aspect of the present invention, when the first cylinder group is composed of one cylinder, the fuel injection rate of the first cylinder group is the average of the second cylinder group. It can be determined that it is smaller than the fuel injection rate.

According to the third aspect of the present invention, when it is determined that the average fuel injection rate of the first cylinder group is smaller than the average fuel injection rate of the second cylinder group, the combined exhaust gas The fuel injection time of the first and second cylinder groups is feedback-corrected until the air-fuel ratio becomes the stoichiometric air-fuel ratio, and the average fuel injection rate of the first cylinder group and the second fuel injection time are calculated based on the feedback correction amount. 3. The apparatus according to claim 2, further comprising a calculating unit configured to calculate a ratio of an average fuel injection rate of the cylinder group to an average fuel injection rate.
A fuel injection amount control device for a multi-cylinder internal combustion engine described in (1) is provided.

According to a third aspect of the present invention, when the first cylinder group is constituted by one cylinder, the fuel injection rate of the first cylinder group and the average of the second cylinder group are determined. The ratio with the fuel injection rate can be calculated.

According to a fourth aspect of the present invention, there is provided the fuel injection amount control apparatus for a multi-cylinder internal combustion engine according to the first aspect, wherein the determination is made during a steady operation of the internal combustion engine. .

According to a fourth aspect of the present invention, there is provided a fuel injection amount control apparatus for a multi-cylinder internal combustion engine, which determines whether the average fuel injection rate of the first cylinder group is equal to the average fuel injection rate of the second cylinder group. Decisions can be made.

According to the fifth aspect of the present invention, the execution of the determination is prohibited in a predetermined rotational speed range of the internal combustion engine. An injection amount control device is provided.

According to a fifth aspect of the present invention, there is provided a fuel injection amount control device for a multi-cylinder internal combustion engine, wherein the average fuel injection rate of the first cylinder group and the second cylinder group are, for example, in a rotational speed range where the influence of intake and exhaust pulsations is large. Erroneous determination as to whether the average fuel injection rate is equal to the average fuel injection rate can be prevented.

According to the present invention, the average fuel injection rate of the first cylinder group is equal to the average fuel injection rate of the second cylinder group in a predetermined rotation speed range of the internal combustion engine. When it is determined that the fuel injection time is smaller than the stoichiometric air-fuel ratio, the fuel injection times of the first and second cylinder groups are feedback-corrected until the merged exhaust gas reaches the stoichiometric air-fuel ratio. 3. The apparatus according to claim 2, further comprising a calculating unit configured to calculate a ratio between an average fuel injection rate of the first cylinder group and an average fuel injection rate of the second cylinder group based on the value. A fuel injection amount control device for a multi-cylinder internal combustion engine is provided.

The fuel injection amount control apparatus for a multi-cylinder internal combustion engine according to the present invention has an advantage that the average fuel injection rate of the first cylinder group and the second cylinder are maintained even in a rotational speed range where the influence of intake and exhaust pulsations is large. The ratio to the average fuel injection rate of the group can be calculated relatively accurately.

According to the seventh aspect of the invention, the cylinders are divided into a first cylinder group and a second cylinder group, and the total amount supplied to the first cylinder group and the second cylinder group is divided. Supply fuel amount change detecting means for detecting a change in the fuel amount, and during a steady operation of the internal combustion engine, increase the fuel injection time of the first cylinder group by a fixed rate and reduce the fuel injection time of the second cylinder group. The fixed ratio x (the number of cylinders in the first cylinder group / the number of cylinders in the second cylinder group) is reduced, or the fuel injection time of the first cylinder group is reduced by a fixed ratio and the second cylinder is reduced. A fuel injection time increasing / decreasing means for increasing the fuel injection time of the group by the fixed ratio × (the number of cylinders of the first cylinder group / the number of cylinders of the second cylinder group); Based on the change in fuel amount, the average fuel injection rate of the first cylinder group A determination means for determining whether or not the average fuel injection rate of the second cylinder group is equal to the average fuel injection rate of the second cylinder group.

A fuel injection amount control device for a multi-cylinder internal combustion engine according to claim 7 determines whether or not the average fuel injection rate of the first cylinder group is equal to the average fuel injection rate of the second cylinder group. You can judge. That is, when the first cylinder group is constituted by one cylinder, it can be determined whether or not the fuel injection rate of that cylinder is equal to the average fuel injection rate of the second cylinder group.

According to an eighth aspect of the present invention, the fuel injection time increasing / decreasing means increases the fuel injection time of the first cylinder group by a fixed ratio and sets the fuel injection time of the second cylinder group. When the total fuel amount is reduced after reducing the fuel injection time by the fixed ratio × (the number of cylinders of the first cylinder group / the number of cylinders of the second cylinder group), the average fuel injection of the first cylinder group is reduced. The fuel injection amount control device for a multi-cylinder internal combustion engine according to claim 7, wherein it is determined that the rate is smaller than an average fuel injection rate of the second cylinder group.

In the fuel injection amount control device for a multi-cylinder internal combustion engine according to the present invention, when the first cylinder group is composed of one cylinder, the fuel injection rate of that cylinder is the average of the second cylinder group. It can be determined that it is smaller than the fuel injection rate.

According to the ninth aspect of the present invention, when it is determined that the average fuel injection rate of the first cylinder group is smaller than the average fuel injection rate of the second cylinder group, the fuel injection time The fuel injection time of the first and second cylinder groups is feedback-corrected until the total fuel amount after the operation of the increasing / decreasing means does not change, and the average fuel injection rate of the first cylinder group is based on the feedback correction amount. 9. The fuel injection amount control device for a multi-cylinder internal combustion engine according to claim 8, further comprising a calculation unit that calculates a ratio of the second cylinder group to an average fuel injection rate.

In the fuel injection amount control apparatus for a multi-cylinder internal combustion engine according to the ninth aspect, when the first cylinder group is constituted by one cylinder, the fuel injection rate of the cylinder and the average of the second cylinder group are determined. The ratio with the fuel injection rate can be calculated.

[0023]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is an overall schematic diagram showing a first embodiment of a fuel injection amount control device for a multi-cylinder internal combustion engine according to the present invention.
In FIG. 1, an air flow meter 3 is provided in an intake passage 2 of an engine body 1. The air flow meter 3 directly measures the amount of intake air, and has a built-in potentiometer to generate an analog voltage output signal proportional to the amount of intake air. This output signal is supplied to the A / D converter 101 with a built-in multiplexer of the control circuit 10. The distributor 4 has, for example, a crank angle sensor 5 that generates a reference position detection pulse signal every 720 ° in terms of a crank angle and 30 ° in terms of a crank angle.
A crank angle sensor 6 for generating a pulse signal for detecting a reference position is provided every time. The pulse signals of the crank angle sensors 5 and 6 are supplied to an input / output interface 102 of the control circuit 10, and the output of the crank angle sensor 6 is supplied to an interrupt terminal of the CPU 103.

Further, the intake passage 2 is provided with a fuel injection valve 7 for supplying pressurized fuel from a fuel supply system to an intake port for each cylinder. The water jacket 8 of the cylinder block of the engine body 1 is provided with a water temperature sensor 9 for detecting the temperature of the cooling water. The water temperature sensor 9 generates an analog voltage electric signal corresponding to the cooling water temperature THW. This output is also supplied to the A / D converter 101.

The exhaust system downstream of the exhaust manifold 11 has a catalytic converter 12 containing a three-way catalyst for simultaneously purifying three harmful components HC, CO and NOx in the exhaust gas.
Is provided. An O ₂ sensor 13 is provided in the exhaust manifold 11, that is, upstream of the catalytic converter 12. The O ₂ sensor 13 generates an electric signal according to the concentration of the O ₂ component in the exhaust gas. That is, the O ₂ sensor 13 generates a different output voltage to the A / D converter 101 by the control circuit 10 depending on whether the air-fuel ratio is lean or rich with respect to the stoichiometric air-fuel ratio. FIG. 2 is a graph showing an output voltage V generated by the O ₂ sensor 13 according to the air-fuel ratio A / F. As shown in FIG. 2, the output voltage V generated by the O ₂ sensor 13 changes abruptly at the stoichiometric air-fuel ratio. When the air-fuel ratio is lean, an output voltage of about 0.1 V is generated, and when the air-fuel ratio is rich, An output voltage of about 0.9 V is generated.

Returning to FIG. 1, the control circuit 10 is configured as a microcomputer, for example, and the A / D converter 10
1. In addition to the input / output interface 102 and the CPU 103, a ROM 104, a RAM 105, and a backup RAM
106, a clock generation circuit 107, and the like.

In the control circuit 10, the down counter 108, the flip-flop 109, and the driving circuit 1
Reference numeral 10 is for controlling the fuel injection valve 7. That is, when the control circuit 10 calculates the fuel injection amount TAU, the fuel injection amount TAU is preset in the down counter 108 and the flip-flop 109 is also set. As a result, the drive circuit 110 starts energizing the fuel injection valve 7. On the other hand, when the down counter 108 counts a clock signal (not shown) and its carry-out terminal finally becomes "1" level, the flip-flop 1
09 is set, and the drive circuit 110 stops energizing the fuel injection valve 7. That is, the fuel injection valve 7 is energized by the above-described fuel injection amount TAU, so that an amount of fuel corresponding to the fuel injection amount TAU is sent to the combustion chamber of the engine body 1.

The CPU 103 generates an interrupt at A
For example, when the A / D conversion of the / D converter 101 is completed, when the input / output interface 102 receives a pulse signal of the crank angle sensor 6, or when an interrupt signal from the clock generation circuit 107 is received. The intake air amount data Q and the cooling water temperature data THW of the air flow meter 3 are taken in by an A / D conversion routine executed at predetermined time intervals, and are taken into RA.
It is stored in a predetermined area of M105. That is, the RAM 10
5, the data Q and THW are updated every predetermined time. The rotation speed data Ne is calculated by an interruption of the crank angle sensor 6 at every 30 ° CA, and is stored in the RAM.
105 is stored in a predetermined area.

The concept and phenomena underlying the present invention will be described below.
Will be described. First, the idea underlying the present invention is
It is as follows. The internal combustion engine is the first cylinder and the second cylinder
When the fuel injection amount of the first cylinder is
Q₁, The fuel injection amount of the second cylinder is Q_TwoAnd the fuel injection
Radiation Q₁Is the fuel injection amount Q_TwoSmaller than (Q₁<Q_Two)
At this time, the fuel injection amount of the first cylinder is increased by a% (Q₁→
(1 + 0.01a) × Q₁) With fuel injection in the second cylinder
Reduce the amount of radiation by a% (Q_Two→ (1-0.01a) ×
Q_Two), The fuel injection amount of the first cylinder and the fuel of the second cylinder
The total with the injection amount is the total after change (Q₁+ Q_Two+0.0
1a × (Q₁−Q_Two)) Is the total (Q ₁+ Q_Two)
Smaller than.

Next, the phenomena underlying the present invention are as follows. As described above, the O ₂ sensor outputs a voltage according to the concentration of O ₂ molecules in the exhaust gas. In detail, O ₂
The sensor outputs a voltage according to the number of O ₂ molecules reaching the O ₂ sensor element. It should be noted that the O ₂ molecule is much larger than the H ₂ molecule,
It is easier for H ₂ molecules to reach the O ₂ sensor element via the mesh on the O ₂ sensor surface than for O ₂ molecules. As a result, even when the number of O ₂ molecules does not change, that is, even when the actual air-fuel ratio does not change, if the number of H ₂ molecules increases for some reason, it is difficult for the O ₂ molecules to reach the O ₂ sensor element. Therefore, the O ₂ sensor output value is
The air-fuel ratio is shifted to a richer side than the actual air-fuel ratio.

FIG. 3 is a graph showing the relationship between the actual air-fuel ratio and the amount of generated H ₂ molecules. It is known that the amount of generated H ₂ molecules increases in a higher-order function as the actual air-fuel ratio becomes rich, that is, as the fuel injection amount increases, as shown in FIG. For example, when the fuel injection amount is increased by a certain amount from the state where the actual air-fuel ratio is the stoichiometric air-fuel ratio, the amount of increase in H ₂ molecules is only a certain amount from the state where the actual air-fuel ratio is the stoichiometric air-fuel ratio. It is larger than the decrease amount of H ₂ molecules generated when the fuel injection amount is reduced. Therefore, when the fuel injection amount is increased by a certain amount from the state where the actual air-fuel ratio is the stoichiometric air-fuel ratio, the amount by which the output value of the O ₂ sensor is shifted to the rich side due to the presence of H ₂ molecules becomes the actual amount. When the fuel injection amount is reduced by a fixed amount from the state where the air-fuel ratio is the stoichiometric air-fuel ratio, the output value of the O ₂ sensor is shifted to the rich side due to the presence of H ₂ molecules.

Based on the above-described concept and phenomenon, the fuel injection amount of one cylinder is increased and the fuel injection amount of the other cylinder is increased from the state where the total air-fuel ratio of the two cylinders is the stoichiometric air-fuel ratio. How the total air-fuel ratio changes when the amount is reduced will be described in different cases. FIG. 4 is a graph showing changes in the total air-fuel ratio when the fuel injection amounts of the first and second cylinders having the same fuel injection rate are changed. As shown in FIG.
The total air-fuel ratio of the first and second cylinders having the same fuel injection rate is adjusted to the stoichiometric air-fuel ratio. Subsequently, the fuel injection amount of the first cylinder is increased by 10% (the fuel injection time is increased by 10%) and the fuel injection amount of the second cylinder is decreased by 10% (the fuel injection time is reduced by 10%). . As a result, as shown in FIG. 4B, since the total fuel injection amount of the first and second cylinders does not change, the actual air-fuel ratio remains the stoichiometric air-fuel ratio. However, as described with reference to FIG. 3, as the number of H ₂ molecules generated in the first cylinder increases,
H ₂ molecule is reduced which occurs in the second cylinder, and an increased amount of H ₂ molecules generated by the first cylinder is larger than the decrease amount of H ₂ molecules generated in the second cylinder, the first And the total amount of generated H ₂ molecules in the second cylinder increases. Therefore, O ₂ sensor output value is shifted to the rich side, O ₂
The sensor outputs rich.

FIG. 5 shows the change in the total air-fuel ratio when the fuel injection rate of each of the first and second cylinders in which the fuel injection rate of the first cylinder is larger than the fuel injection rate of the second cylinder is changed. FIG. As shown in FIG. 5A, the total air-fuel ratio of the first and second cylinders in which the fuel injection rate of the first cylinder is larger than the fuel injection rate of the second cylinder is adjusted to the stoichiometric air-fuel ratio. I have. Subsequently, the fuel injection amount of the first cylinder is set to 1
The fuel injection amount of the second cylinder is reduced by 10% (the fuel injection time is reduced by 10%) while the fuel injection amount of the second cylinder is increased by 0% (fuel injection time is increased by 10%). As a result, as shown in FIG. 5B, since the original fuel injection amount of the first cylinder is larger than the original fuel injection amount of the second cylinder, the increase amount of the fuel injection amount of the first cylinder is increased. Becomes larger than the decrease amount of the fuel injection amount of the second cylinder. Therefore, the total fuel injection amount of the first and second cylinders increases, and the actual air-fuel ratio changes from the stoichiometric air-fuel ratio to rich. Further, as described with reference to FIG. 3, since the amount of increase in H ₂ molecules generated in the first cylinder is larger than the amount of decrease in H ₂ molecules generated in the second cylinder, the first and second , The total amount of generated H ₂ molecules in the cylinder increases.
Therefore, the O ₂ sensor output value is further shifted to the rich side, and the O ₂ sensor outputs rich.

FIG. 6 shows the change of the total air-fuel ratio when the fuel injection rate of each of the first and second cylinders is changed, wherein the fuel injection rate of the first cylinder is smaller than the fuel injection rate of the second cylinder. FIG. As shown in FIG. 6A, the total air-fuel ratio of the first and second cylinders in which the fuel injection rate of the first cylinder is smaller than the fuel injection rate of the second cylinder is adjusted to the stoichiometric air-fuel ratio. I have. Subsequently, the fuel injection amount of the first cylinder is set to 1
The fuel injection amount of the second cylinder is reduced by 10% (the fuel injection time is reduced by 10%) while the fuel injection amount of the second cylinder is increased by 0% (fuel injection time is increased by 10%). As a result, as shown in FIG. 6B, since the original fuel injection amount of the first cylinder is smaller than the original fuel injection amount of the second cylinder, the increase amount of the fuel injection amount of the first cylinder is increased. Becomes smaller than the decrease amount of the fuel injection amount of the second cylinder. Therefore, the total fuel injection amount of the first and second cylinders decreases, and the actual air-fuel ratio changes from the stoichiometric air-fuel ratio to lean. Further, as described with reference to FIG. 3, since the amount of increase in H ₂ molecules generated in the first cylinder is smaller than the amount of decrease in H ₂ molecules generated in the second cylinder, the first and second , The total amount of generated H ₂ molecules in the cylinder decreases.
Therefore, O ₂ sensor output value is further shifted to the lean side, O ₂ sensor outputs a lean.

That is, when the fuel injection rates of the first and second cylinders are equal and the fuel injection amount of each cylinder is changed so that the total fuel injection amount does not change, the output value of the O ₂ sensor always changes rich. I do. On the other hand, when the fuel injection rates of the first and second cylinders are different, changing the fuel injection amount of each cylinder so that the total fuel injection amount does not change increases the fuel injection amount of the cylinder with the higher fuel injection rate. O ₂ sensor output value when the changes to the rich, the O ₂ sensor output value when increasing the fuel injection quantity of the fuel injection rate is small cylinder changes to the lean. This also applies when the internal combustion engine has three or more cylinders.

FIG. 7 is a graph showing the change in the total air-fuel ratio when the fuel injection amount of each of the first to fourth cylinders having the same fuel injection rate is changed. As shown in FIG. 7A, the total air-fuel ratio of the first to fourth cylinders having the same fuel injection rate is adjusted to the stoichiometric air-fuel ratio. Subsequently, the fuel injection amount of the first cylinder is increased by 3% (the fuel injection time is increased by 3%
Increase) and the fuel injection amount of the second to fourth cylinders by 1
% (The fuel injection time is reduced by 1%). As a result, as shown in FIG. 7B, since the total fuel injection amount of the first to fourth cylinders does not change, the actual air-fuel ratio remains the stoichiometric air-fuel ratio. However, as described with reference to FIG. 3, with H ₂ molecules generated by the first cylinder increases, H ₂ molecule from the second to occur in the fourth cylinder is reduced, and, first increase of H ₂ molecules generated in the cylinder is larger than the decrease amount of H ₂ molecules occurring in the fourth cylinder from the second, the amount of the sum of H ₂ molecules in the fourth cylinder from the first increase I do. Therefore, the O ₂ sensor output value is shifted to the rich side, and the O ₂ sensor outputs rich.

FIG. 8 shows that the fuel injection rates of the second cylinder are the first and second fuel injection rates.
The first greater than the average fuel injection rate of the third and fourth cylinders
Change the fuel injection amount of each of the fourth cylinders
It is the graph which showed the change of the total air-fuel ratio. FIG. 8 (a)
As shown in the figure, the fuel injection rate of the second cylinder
The first to fourth cylinders that are larger than the average fuel injection rate of the fourth and fourth cylinders
The total air-fuel ratio of the four cylinders is adjusted to the stoichiometric air-fuel ratio.
You. Subsequently, the fuel injection amount of the second cylinder is increased by 3%.
(Increase fuel injection time by 3%)
Reduce the fuel injection amount of the fourth cylinder by 1% (fuel injection time
1%). As a result, as shown in FIG.
In addition, the original fuel injection amount of the second cylinder is changed to the first, third, and fourth cylinders.
Is larger than the original average fuel injection amount of the cylinder
The amount of increase in the fuel injection amount of the cylinder is the first, third and fourth cylinders.
Is larger than the decrease amount of the fuel injection amount. Therefore,
The total fuel injection amount of the first to fourth cylinders increases,
The air-fuel ratio changes richly from the stoichiometric air-fuel ratio. Further, FIG.
As described with reference to, H generated in the second cylinder_Two
H generated in the first, third and fourth cylinders due to the increase in the number of molecules
_TwoThe first and second cylinders are larger than the molecular depletion
H in_TwoThe total amount of molecules generated increases. That
O_TwoThe sensor output value is further shifted to the rich side, and O
_TwoThe sensor outputs rich.

FIG. 9 shows the total empty space when the fuel injection amount of each of the first to fourth cylinders in which the fuel injection rate of the first cylinder is smaller than the fuel injection rate of the second to fourth cylinders is changed. 4 is a graph showing a change in fuel ratio. As shown in FIG. 9A, the total air-fuel ratio of the first to fourth cylinders in which the fuel injection rate of the first cylinder is smaller than the fuel injection rate of the second to fourth cylinders becomes the stoichiometric air-fuel ratio. Has been adjusted. Subsequently, the fuel injection amount of the first cylinder is increased by 3% (the fuel injection time is increased by 3%), and the fuel injection amount of the second to fourth cylinders is reduced by 1% (the fuel injection time is reduced by 1%). Decrease). as a result,
As shown in FIG. 9B, since the original fuel injection amount of the first cylinder is smaller than the original fuel injection amount of the second to fourth cylinders, the increase amount of the fuel injection amount of the first cylinder is increased. Becomes smaller than the decrease amount of the fuel injection amount of the second to fourth cylinders. Therefore, the total fuel injection amount of the first to fourth cylinders decreases,
The actual air-fuel ratio changes from the stoichiometric air-fuel ratio to lean. Further, as described with reference to FIG. 3, the amount of increase in H ₂ molecules generated in the first cylinder is smaller than the amount of decrease in H ₂ molecules generated in the second to fourth cylinders. Therefore, the total amount of generated H ₂ molecules in the fourth cylinder decreases. Therefore, the O ₂ sensor output value is further shifted to the lean side,
_Two sensors output lean.

That is, when the fuel injection rates of the first to fourth cylinders are equal, if the fuel injection amount of each cylinder is changed so that the total fuel injection amount does not change, the output value of the O ₂ sensor always changes rich. I do. On the other hand, when the fuel injection rates of the first to fourth cylinders are different, changing the fuel injection amount of each cylinder so that the total fuel injection amount does not change increases the fuel injection amount of the cylinder with the larger fuel injection rate. O ₂ sensor output value when the changes to the rich, the O ₂ sensor output value when increasing the fuel injection quantity of the fuel injection rate is small cylinder changes to the lean.

Returning to the description of the present embodiment, the fuel injection amount control method of the fuel injection amount control device for a multi-cylinder internal combustion engine of the present embodiment will be described below. FIGS. 10 and 11 are flowcharts showing the fuel injection amount control method according to the present embodiment. As shown in FIG. 10, when the fuel injection amount control device for the multi-cylinder internal combustion engine of the present embodiment starts the fuel injection amount control,
First, in step 1001, it is determined whether the internal combustion engine is in a warm-up operation. During the warm-up operation, the routine is terminated without executing the fuel injection amount control of the present embodiment because the fuel injection amount control of the present embodiment is not suitable for execution. On the other hand, when the engine is not in the warm-up operation, it is determined in step 1002 whether the internal combustion engine is in the normal operation. When the engine is not in the steady operation, that is, when the air-fuel ratio is not the stoichiometric air-fuel ratio, the routine is terminated without executing the fuel injection amount control of the present embodiment because the fuel injection amount control of the present embodiment is not suitable. On the other hand, when the engine is in a steady operation, that is, when the air-fuel ratio is the stoichiometric air-fuel ratio, in step 1003, the plurality of cylinders of the internal combustion engine are divided into a first cylinder group and a second cylinder group.

Subsequently, at step 1004, the fuel injection amount of the first cylinder group is increased, that is, the fuel injection time of the first cylinder group is increased by a fixed ratio, and the fuel injection amount of the second cylinder group is increased. The amount is reduced, that is, the fuel injection time of the second cylinder group is reduced by the certain ratio × (the number of cylinders of the first cylinder group / the number of cylinders of the second cylinder group). Subsequently, at step 1005, the O ₂ sensor 13 detects the air-fuel ratio of the exhaust gas discharged from the first and second cylinder groups and merged. Subsequently, in step 1006, it is determined whether or not the output value of the O ₂ sensor is lean. When the output value is lean, the average fuel injection rate of the first cylinder group is calculated from the average fuel injection rate of the second cylinder group. Step 1010
Move to On the other hand, if not lean, step 10
Shift to 07.

In step 1007, the fuel injection amount of the first cylinder group is reduced, that is, the fuel injection time of the first cylinder group is reduced by a fixed ratio, and the fuel injection amount of the second cylinder group is increased. That is, the fuel injection time of the second cylinder group is set to the predetermined ratio × (the number of cylinders of the first cylinder group /
(The number of cylinders in the second cylinder group). Subsequently, at step 1008, the air-fuel ratio of the exhaust gas discharged from the first and second cylinder groups and joined by the O ₂ sensor 13 is detected. Subsequently, in step 1009, it is determined whether or not the output value of the O ₂ sensor is lean. When the output value is lean, the average fuel injection rate of the first cylinder group is calculated from the average fuel injection rate of the second cylinder group. Step 1010
Move to On the other hand, when the engine is not lean, it is determined that the average fuel injection rate of the first cylinder group is equal to the average fuel injection rate of the second cylinder group, and the flow shifts to step 1013.

In step 1010, the fuel injection times of the first and second cylinder groups are feedback-corrected until the air-fuel ratio of the exhaust gas discharged from the first and second cylinder groups and merged becomes the stoichiometric air-fuel ratio. In step 1011, a total correction amount is calculated. Subsequently, in step 1012, a ratio between the average fuel injection rate of the first cylinder group and the average fuel injection rate of the second cylinder group is calculated based on the total correction amount. Subsequently, in Step 1013, Step 1004, Step 1
The fuel injection times of the first and second cylinder groups changed in step 007 and step 1010 are restored.

Subsequently, at step 1014, it is determined whether or not the ratio of the fuel injection rate for each cylinder of the internal combustion engine has been grasped. If the ratio of the fuel injection rate for all cylinders has not been grasped yet, Returning to step 1003, the combination of the cylinders forming the first and second cylinder groups is changed, and the above-described steps are repeated. On the other hand, when the ratios of the fuel injection rates for all the cylinders can be determined, step 10 is executed.
Move to 15. In step 1015, the fuel injection amount of each cylinder is corrected so that the fuel injection amounts of all cylinders are equal, that is, the fuel injection time of each cylinder is corrected,
This routine ends. In the present embodiment, it is possible to absorb not only the variation in the fuel injection rate of each cylinder but also the variation between cylinders due to the valve system and the intake and exhaust pulsation. Therefore, it is possible to avoid an increase in the catalyst capacity for absorbing the variation in the fuel injection rate of each cylinder and an increase in cost due to the arrangement of the O ₂ sensor on the downstream side of the catalyst.

In this embodiment, when the internal combustion engine is in the warm-up operation in step 1001 or when the internal combustion engine is not in the steady operation in step 1002, that is, when the air-fuel ratio is not the stoichiometric air-fuel ratio, This routine is ended without executing the fuel injection amount control of the present embodiment. However, in the other embodiments, Step 1003 is performed instead.
Step 1011 is continuously executed, and subsequently, the ratio between the average fuel injection rate of the first cylinder group and the average fuel injection rate of the second cylinder group is determined based on the total correction amount and a predetermined learning value. It may be calculated. In still another embodiment, the correction of the fuel injection amount may be prohibited in the rotation speed range of the internal combustion engine where the influence of the intake and exhaust pulsations is strong. Alternatively, in a variable valve system or a variable intake / exhaust system, a learning value may be provided for each variable mechanism.

FIG. 12 is an overall schematic diagram showing a second embodiment of a fuel injection amount control system for a multi-cylinder internal combustion engine according to the present invention. In FIG. 12, reference numeral 60 denotes a four-cylinder internal combustion engine main body, and a fuel injection valve 57 is provided for each cylinder. Each fuel injection valve 57 is connected to a common accumulator 61.
Reference numeral 62 denotes a general fuel pump for discharging fuel to the pressure accumulating chamber 61, which is driven by the engine main body 60. The fuel pump 62 is provided with two cylinders 62 a and 62 b, each of which is connected to a high-pressure pipe 63 connected to the accumulator 61.
Each check valve 62 allowing only the fuel flow in the direction of the accumulator
c, 62d. Numeral 64 denotes a fuel passage connecting the fuel pump 62 and the fuel tank 65, and a feed pump 6 for providing a fuel flow toward the fuel pump.
4a is arranged.

The feed pump 64 in the fuel passage 64
Downstream from a, a pressure regulator 64c for returning excess fuel to the fuel tank 65 via the return passage 64b when the pressure in the fuel passage 64 becomes equal to or higher than a predetermined pressure is disposed.
First and second cylinders 62a, 62b of fuel pump 62
The first and second solenoid valves 6 are provided in such a fuel passage 64.
They are connected via 2e and 62f. 66 is a pressure sensor for detecting the fuel pressure in the accumulator 11.
That is, by detecting the fuel pressure in the accumulator 11 after the fuel injection by the pressure sensor 66 at each injection timing, it is determined whether or not the total amount of fuel injected from each cylinder changes at each injection timing. be able to. still,
In another embodiment, instead of grasping the change in the total fuel amount based on the output value of the pressure sensor 66, the pressure sensor 6
6, the first and second solenoid valves 62 that change based on the output value
The change in the total fuel amount may be grasped from the duty ratios e and 62f.

Returning to the description of the second embodiment, reference numeral 70 designates a control device for controlling the fuel injection of the fuel injection valve 57 together with the discharge control of the fuel pump 62. For example, a rotation sensor 71 for detecting the engine speed, an air flow meter 72 for detecting the intake air amount, and a cooling water temperature sensor 73 for detecting the engine cooling water temperature as the engine temperature. Etc. are connected.

The fuel pump 62 has the above-described structure, and performs two fuel discharges to the accumulator 61 by the first and second cylinders during one cycle in which all the fuel injection valves complete the fuel injection. Is implemented. The first cylinder 62a reaches the discharge stroke in the first half of the above-described fuel injection cycle, and in this discharge stroke, the first solenoid valve 62
e, the fuel is discharged only while the valve is closed, whereby the opening and closing control of the first solenoid valve 62e allows the fuel discharge timing and the discharged fuel amount to be freely set in the first half of the fuel injection cycle. Has become. Similarly, the second cylinder 62b can freely set the fuel discharge timing and the discharged fuel amount in the latter half of the fuel injection cycle by controlling the opening and closing of the second solenoid valve 62f.

Also in this embodiment, the present invention
The underlying idea is used. In other words, the internal combustion engine
When configured with one cylinder and a second cylinder, the first
The fuel injection amount of the cylinder is Q₁, The fuel injection amount of the second cylinder is
Q_TwoAnd the fuel injection amount Q ₁Is the fuel injection amount Q_Twothan
Small (Q₁<Q_Two) When the fuel injection amount of the first cylinder is
a% increase (Q₁→ (1 + 0.01a) × Q₁) And
The fuel injection amount of the second cylinder is reduced by a% (Q_Two→ (1
-0.01a) × Q_Two), And the fuel injection amount of the first cylinder
The total with the fuel injection amount of the second cylinder is the total after the change (Q
₁+ Q_Two+ 0.01a × (Q₁−Q_Two)) Is the same as before
Total (Q₁+ Q_Two).

Based on the above-described concept, the total fuel amount supplied to the two cylinders will be changed from a state where the total amount is a certain value.
How the total fuel amount changes when the fuel injection amount of one cylinder is increased and the fuel injection amount of the other cylinder is reduced will be described in different cases. FIG. 13 is a graph showing changes in the total air-fuel ratio when the fuel injection amounts of the first and second cylinders having the same fuel injection rate are changed. As shown in FIG. 13A, the total fuel amount of the first and second cylinders having the same fuel injection rate is adjusted to 200. Subsequently, the fuel injection amount of the first cylinder is set to 10
% And the fuel injection amount of the second cylinder is reduced by 10% (the fuel injection time is reduced by 10%). As a result, as shown in FIG. 13B, the total fuel amount of the first and second cylinders does not change.

FIG. 14 shows the change in the total fuel amount when the fuel injection rate of each of the first and second cylinders is changed, where the fuel injection rate of the first cylinder is larger than the fuel injection rate of the second cylinder. It is a graph shown. As shown in FIG. 14A, the total fuel amount of the first and second cylinders in which the fuel injection rate of the first cylinder is larger than the fuel injection rate of the second cylinder is adjusted to 198. Subsequently, the fuel injection amount of the first cylinder is reduced by 10%.
The fuel injection amount of the second cylinder is reduced by 10% (the fuel injection time is reduced by 10%) while the fuel injection time is increased (fuel injection time is increased by 10%). As a result, as shown in FIG. 14B, since the original fuel injection amount of the first cylinder is larger than the original fuel injection amount of the second cylinder, the increase amount of the fuel injection amount of the first cylinder is increased. Becomes larger than the decrease amount of the fuel injection amount of the second cylinder. Therefore, the total fuel amount of the first and second cylinders increases to 199.

FIG. 15 shows the change in the total fuel amount when the fuel injection amount of each of the first and second cylinders is changed, in which the fuel injection rate of the first cylinder is smaller than the fuel injection rate of the second cylinder. It is a graph shown. As shown in FIG. 15A, the total fuel amount of the first and second cylinders in which the fuel injection rate of the first cylinder is smaller than the fuel injection rate of the second cylinder is adjusted to 198. Subsequently, the fuel injection amount of the first cylinder is reduced by 10%.
The fuel injection amount of the second cylinder is reduced by 10% (the fuel injection time is reduced by 10%) while the fuel injection time is increased (fuel injection time is increased by 10%). As a result, as shown in FIG. 15B, since the original fuel injection amount of the first cylinder is smaller than the original fuel injection amount of the second cylinder, the increase amount of the fuel injection amount of the first cylinder is increased. Becomes smaller than the decrease amount of the fuel injection amount of the second cylinder. Therefore, the total fuel amount of the first and second cylinders is reduced to 196.

That is, when the fuel injection rates of the first and second cylinders are equal, the total fuel amount does not change. On the other hand, when the fuel injection rates of the first and second cylinders are different, the total fuel amount increases when the fuel injection rate of the cylinder with the higher fuel injection rate is increased, and the fuel injection rate of the cylinder with the lower fuel injection rate is increased. When is increased, the total fuel amount decreases. This also applies when the internal combustion engine has three or more cylinders.

FIG. 16 is a graph showing a change in the total air-fuel ratio when the fuel injection amount of each of the first to fourth cylinders having the same fuel injection rate is changed. As shown in FIG. 16A, the total fuel amount of the first to fourth cylinders having the same fuel injection rate is adjusted to a certain value. Subsequently, the fuel injection amount of the first cylinder is increased by 3% (the fuel injection time is increased by 3%).
%) And the fuel injection amount of the second to fourth cylinders is reduced by 1% (the fuel injection time is reduced by 1%). As a result, as shown in FIG. 16B, the total fuel amount of the first to fourth cylinders does not change.

FIG. 17 shows that the fuel injection rate of the second cylinder is first,
9 is a graph showing a change in the total fuel amount when the fuel injection amount of each of the first to fourth cylinders, which is larger than the average fuel injection rate of the third and fourth cylinders, is changed. FIG.
As shown in (a), the fuel injection rate of the second cylinder is first,
The total fuel amount of the first to fourth cylinders larger than the average fuel injection rate of the third and fourth cylinders is adjusted to a certain value. Subsequently, the fuel injection amount of the second cylinder is increased by 3% (the fuel injection time is increased by 3%), and the fuel injection amount of the first, third, and fourth cylinders is reduced by 1% (fuel injection time). 1%). As a result, as shown in FIG. 17B, the original fuel injection amount of the second cylinder is larger than the original average fuel injection amount of the first, third, and fourth cylinders. Is larger than the decrease in the fuel injection amount of the first, third, and fourth cylinders. therefore,
The total fuel injection amount of the first to fourth cylinders increases.

FIG. 18 shows the total fuel amount when the fuel injection rate of each of the first to fourth cylinders in which the fuel injection rate of the first cylinder is smaller than the fuel injection rate of the second to fourth cylinders is changed. 6 is a graph showing a change in the graph. As shown in FIG. 18A, the total fuel amount of the first to fourth cylinders in which the fuel injection rate of the first cylinder is smaller than the fuel injection rate of the second to fourth cylinders is adjusted to a certain value. Have been. Subsequently, the fuel injection amount of the first cylinder is increased by 3% (the fuel injection time is increased by 3%), and the fuel injection amount of the second to fourth cylinders is reduced by 1% (the fuel injection time is reduced by 1%). Decrease). as a result,
As shown in FIG. 18B, since the original fuel injection amount of the first cylinder is smaller than the original fuel injection amount of the second to fourth cylinders, the increase amount of the fuel injection amount of the first cylinder is increased. Becomes smaller than the decrease amount of the fuel injection amount of the second to fourth cylinders. Therefore, the total fuel amount of the first to fourth cylinders decreases.

That is, when the fuel injection rates of the first to fourth cylinders are equal, the total fuel amount does not change. On the other hand, when the fuel injection rates of the first and second cylinders are different, the total fuel amount increases when the fuel injection rate of the cylinder with the higher fuel injection rate is increased, and the fuel injection rate of the cylinder with the lower fuel injection rate is increased. When is increased, the total fuel amount decreases.

Returning to the description of the present embodiment, the fuel injection amount control method of the fuel injection amount control device for a multi-cylinder internal combustion engine of the present embodiment will be described below. FIG. 19 and FIG. 20 are flowcharts showing the fuel injection amount control method of the present embodiment. As shown in FIG. 19, when the fuel injection amount control device for the multi-cylinder internal combustion engine of the present embodiment starts the fuel injection amount control,
First, in step 2001, it is determined whether or not the internal combustion engine is in a warm-up operation. During the warm-up operation, the routine is terminated without executing the fuel injection amount control of the present embodiment because the fuel injection amount control of the present embodiment is not suitable for execution. On the other hand, when the engine is not in the warm-up operation, it is determined in step 2002 whether the internal combustion engine is in the normal operation. When it is not during the steady operation, the routine is terminated without executing the fuel injection amount control of the present embodiment because it is not suitable for the execution of the fuel injection amount control of the present embodiment. On the other hand, when the vehicle is in a steady operation, step 200
At 3, the plurality of cylinders of the internal combustion engine are divided into a first cylinder group and a second cylinder group.

Subsequently, in step 2004, the fuel injection amount of the first cylinder group is increased, that is, the fuel injection time of the first cylinder group is increased by a certain ratio, and the fuel injection amount of the second cylinder group is increased. The amount is reduced, that is, the fuel injection time of the second cylinder group is reduced by the certain ratio × (the number of cylinders of the first cylinder group / the number of cylinders of the second cylinder group). Subsequently, in step 2005, a change in the total fuel amount of the first and second cylinder groups is detected by the pressure sensor 66, that is, before and after changing the fuel injection time of the first and second cylinder groups. To detect whether the total fuel amount has changed. Subsequently, in step 2006, it is determined whether or not the total fuel amount has increased. If the total fuel amount has increased, it is determined that the average fuel injection rate of the first cylinder group is larger than the average fuel injection rate of the second cylinder group. Then, the process proceeds to step 2008. On the other hand, if it has not increased, it is determined in step 2007 whether or not the total fuel amount has decreased. If the total fuel amount has decreased, the average fuel injection rate of the first cylinder group has decreased to the average fuel injection rate of the second cylinder group. It is determined that it is smaller than the threshold value, and the process proceeds to step 2008. On the other hand, when the total fuel amount does not change, it is determined that the average fuel injection rate of the first cylinder group is equal to the average fuel injection rate of the second cylinder group, and the routine proceeds to step 2011.

In step 2008, step 20
The fuel injection time of the first and second cylinder groups is feedback corrected until the total fuel amount does not change when the fuel injection time of the first and second cylinder groups is changed similarly to 04,
In step 2009, a total correction amount is calculated. Subsequently, in step 2010, the ratio between the average fuel injection rate of the first cylinder group and the average fuel injection rate of the second cylinder group is calculated based on the total correction amount. Subsequently, in step 2011, the fuel injection times of the first and second cylinder groups changed in step 2004 and step 2008 are returned to the original.

Subsequently, at step 2012, it is determined whether or not the ratio of the fuel injection rate for each cylinder of the internal combustion engine has been grasped. If the ratio of the fuel injection rate for each cylinder has not been grasped yet, Returning to step 2003, the combination of the cylinders constituting the first and second cylinder groups is changed, and the above-described steps are repeated. On the other hand, when the ratios of the fuel injection rates for all the cylinders can be determined, step 20 is executed.
Go to step 13. In step 2013, the fuel injection amount of each cylinder is corrected so that the fuel injection amount of all cylinders becomes equal, that is, the fuel injection time of each cylinder is corrected,
This routine ends. In the present embodiment, similarly to the first embodiment, not only the variation in the fuel injection rate of each cylinder but also the variation between the cylinders due to the valve system and the intake and exhaust pulsation can be absorbed. Therefore, it is possible to avoid an increase in the catalyst capacity for absorbing the variation in the fuel injection rate of each cylinder and an increase in cost due to the arrangement of the O ₂ sensor on the downstream side of the catalyst. Further, in the present embodiment, unlike the first embodiment, an O ₂ sensor is not required for correcting the above-described fuel injection amount.

[0064]

According to the first and seventh aspects of the present invention,
Determine whether the average fuel injection rate of the first cylinder group and the average fuel injection rate of the second cylinder group are equal, that is, the average fuel injection rate of the first cylinder group and the second cylinder group Can be determined.

According to the second and eighth aspects of the present invention, it is determined that the average fuel injection rate of the first cylinder group is smaller than the average fuel injection rate of the second cylinder group. It is possible to determine which of the groups and the second cylinder group has the smaller average fuel injection rate.

According to the third and ninth aspects, it is possible to calculate the ratio between the average fuel injection rate of the first cylinder group and the average fuel injection rate of the second cylinder group.

According to the fourth aspect of the present invention, it is possible to accurately determine whether the average fuel injection rate of the first cylinder group is equal to the average fuel injection rate of the second cylinder group. .

According to the fifth aspect of the present invention, the average fuel injection rate of the first cylinder group and the average fuel injection rate of the second cylinder group are different, for example, in a rotation speed range where the influence of intake and exhaust pulsations is large. It is possible to prevent an erroneous determination as to whether or not they are equal.

According to the present invention, the average fuel injection rate of the first cylinder group and the average fuel injection rate of the second cylinder group can be reduced even in a rotational speed range where the influence of intake and exhaust pulsations is large. Can be calculated relatively accurately.

[Brief description of the drawings]

FIG. 1 is an overall schematic diagram showing a first embodiment of a fuel injection amount control device for a multi-cylinder internal combustion engine of the present invention.

FIG. 2 is a graph showing an output voltage V generated by an O ₂ sensor according to an air-fuel ratio A / F.

FIG. 3 is a graph showing a relationship between an actual air-fuel ratio and an amount of generated H ₂ molecules.

FIG. 4 is a graph showing a change in the total air-fuel ratio when the fuel injection amount of each of the first and second cylinders having the same fuel injection rate is changed.

FIG. 5 shows a change in the total air-fuel ratio when the fuel injection amount of each of the first and second cylinders in which the fuel injection rate of the first cylinder is larger than the fuel injection rate of the second cylinder is changed. FIG.

FIG. 6 shows a change in the total air-fuel ratio when the fuel injection rate of each of the first and second cylinders in which the fuel injection rate of the first cylinder is smaller than the fuel injection rate of the second cylinder is changed. FIG.

FIG. 7 is a graph showing a change in the total air-fuel ratio when the fuel injection amount of each of the first to fourth cylinders having the same fuel injection rate is changed.

FIG. 8 shows the sum when the fuel injection amount of each of the first to fourth cylinders in which the fuel injection rate of the second cylinder is greater than the average fuel injection rate of the first, third, and fourth cylinders; 5 is a graph showing a change in the air-fuel ratio of the present invention.

FIG. 9 shows the total air-fuel ratio when the fuel injection amount of each of the first to fourth cylinders in which the fuel injection rate of the first cylinder is smaller than the fuel injection rate of the second to fourth cylinders is changed. It is a graph which showed a change.

FIG. 10 is a flowchart illustrating a fuel injection amount control method according to the present embodiment.

FIG. 11 is a flowchart illustrating a fuel injection amount control method according to the present embodiment.

FIG. 12 is an overall schematic diagram showing a second embodiment of a fuel injection amount control device for a multi-cylinder internal combustion engine of the present invention.

FIG. 13 is a graph showing changes in the total fuel amount when the fuel injection amounts of the first and second cylinders having the same fuel injection rate are changed.

FIG. 14 shows a change in the total fuel amount when the fuel injection amount of each of the first and second cylinders in which the fuel injection rate of the first cylinder is larger than the fuel injection rate of the second cylinder is changed. It is a graph.

FIG. 15 shows a change in the total fuel amount when the fuel injection amount of each of the first and second cylinders in which the fuel injection rate of the first cylinder is smaller than the fuel injection rate of the second cylinder is changed. It is a graph.

FIG. 16 is a graph showing a change in the total fuel amount when the fuel injection amount of each of the first to fourth cylinders having the same fuel injection rate is changed.

FIG. 17 shows the sum when the fuel injection amount of each of the first to fourth cylinders in which the fuel injection rate of the second cylinder is larger than the average fuel injection rate of the first, third and fourth cylinders is changed. 5 is a graph showing a change in a fuel amount.

FIG. 18 shows a change in the total fuel amount when the fuel injection rate of each of the first to fourth cylinders in which the fuel injection rate of the first cylinder is smaller than the fuel injection rate of the second to fourth cylinders is changed. FIG.

FIG. 19 is a flowchart illustrating a fuel injection amount control method according to the present embodiment.

FIG. 20 is a flowchart illustrating a fuel injection amount control method according to the present embodiment.

[Explanation of symbols]

10 ... control circuit 13 ... O ₂ sensor

Claims (9)

[Claims] 1. A cylinder group is divided into a first cylinder group and a second cylinder group, and an air-fuel ratio of exhaust gas discharged from the first cylinder group and the second cylinder group and merged is detected. When the air-fuel ratio of the combined exhaust gas is a stoichiometric air-fuel ratio, the fuel injection time of the first cylinder group is increased by a fixed rate, and the fuel injection time of the second cylinder group is increased. The fuel injection time of the first cylinder group is reduced by a certain ratio × (the number of cylinders of the first cylinder group / the number of cylinders of the second cylinder group), or the second cylinder group is reduced. Fuel injection time increasing / decreasing means for increasing the fuel injection time by the fixed ratio × (the number of cylinders in the first cylinder group / the number of cylinders in the second cylinder group), and the exhaust gas joined after the operation of the fuel injection time increasing / decreasing means. Average fuel injection of the first cylinder group based on the air-fuel ratio of the gas And said second fuel injection amount of the multi-cylinder internal combustion engine having a judgment means for the average fuel injection rate of cylinder group to determine whether equal controller. 2. The fuel cell system according to claim 1, wherein the fuel injection time increasing / decreasing means increases the fuel injection time of the first cylinder group by a fixed rate and increases the fuel injection time of the second cylinder group by the fixed rate × ( (The number of cylinders in the first cylinder group / the number of cylinders in the second cylinder group), and when the air-fuel ratio of the combined exhaust gas is lean, the average fuel injection rate of the first cylinder group is reduced by the 2. The fuel injection amount control device for a multi-cylinder internal combustion engine according to claim 1, wherein it is determined that the average fuel injection rate is smaller than an average fuel injection rate of the two cylinder groups. 3. When the average fuel injection rate of the first cylinder group is determined to be smaller than the average fuel injection rate of the second cylinder group, the air-fuel ratio of the combined exhaust gas becomes the stoichiometric air-fuel ratio. The fuel injection time of the first and second cylinder groups is feedback corrected until the average fuel injection rate of the first cylinder group and the average fuel injection rate of the second cylinder group are corrected based on the feedback correction amount. 3. The fuel injection amount control device for a multi-cylinder internal combustion engine according to claim 2, further comprising a calculating unit that calculates a ratio. 4. The fuel injection amount control device for a multi-cylinder internal combustion engine according to claim 1, wherein the determination is made during a steady operation of the internal combustion engine. 5. The fuel injection amount control device for a multi-cylinder internal combustion engine according to claim 1, wherein the execution of the determination is prohibited in a predetermined rotational speed range of the internal combustion engine. 6. When it is determined that an average fuel injection rate of the first cylinder group is smaller than an average fuel injection rate of the second cylinder group in a predetermined rotation speed range of the internal combustion engine, The fuel injection times of the first and second cylinder groups are feedback-corrected until the air-fuel ratio of the combined exhaust gas reaches the stoichiometric air-fuel ratio, and the first fuel injection time is determined based on the feedback correction amount and a predetermined learning value. 3. The fuel injection amount control for a multi-cylinder internal combustion engine according to claim 2, further comprising a calculating unit that calculates a ratio between an average fuel injection rate of the cylinder group and an average fuel injection rate of the second cylinder group. apparatus. 7. A supply fuel for dividing a cylinder into a first cylinder group and a second cylinder group, and detecting a change in a total amount of fuel supplied to the first cylinder group and the second cylinder group. An amount change detecting means for increasing the fuel injection time of the first cylinder group by a fixed ratio and increasing the fuel injection time of the second cylinder group by the fixed ratio × (first cylinder during the steady operation of the internal combustion engine) (The number of cylinders in the group / the number of cylinders in the second cylinder group), or the fuel injection time of the first cylinder group is reduced by a fixed rate, and the fuel injection time of the second cylinder group is reduced by the fixed rate. X (the number of cylinders in the first cylinder group / the number of cylinders in the second cylinder group) and a fuel injection time increasing / decreasing means, and a change in the total fuel amount after the fuel injection time increasing / decreasing means operates. Average fuel injection rate of the first cylinder group and average fuel injection of the second cylinder group DOO fuel injection amount control apparatus for a multi-cylinder internal combustion engine having a determination means for determining whether equal. 8. The determining means, wherein the fuel injection time increasing / decreasing means increases the fuel injection time of the first cylinder group by a fixed rate and increases the fuel injection time of the second cylinder group by the fixed rate × ( (The number of cylinders in the first cylinder group / the number of cylinders in the second cylinder group), and when the total fuel amount decreases, the average fuel injection rate of the first cylinder group decreases. The fuel injection amount control device for a multi-cylinder internal combustion engine according to claim 7, wherein it is determined that the fuel injection amount is smaller than the average fuel injection rate. 9. The total fuel amount after activation of the fuel injection time increasing / decreasing means when it is determined that the average fuel injection rate of the first cylinder group is smaller than the average fuel injection rate of the second cylinder group. The fuel injection time of the first and second cylinder groups is feedback-corrected until the value no longer changes, and based on the feedback correction amount, the average fuel injection rate of the first cylinder group and the average fuel of the second cylinder group 9. The fuel injection amount control device for a multi-cylinder internal combustion engine according to claim 8, further comprising a calculation unit that calculates a ratio to an injection rate.