JPH11241630A - Fuel injection control system for multiple cylinder internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To control misfire caused by an increasingly corrected fuel injection in a multiple cylinder internal combustion engine which can correct the amount of fuel injection according to the amount of fuel injection for each cylinder calculated so as to uniform rotation fluctuation among cylinders. SOLUTION: An electronic controller unit(ECU) 30 for an engine 1 capable of stratified combustion increases and corrects fuel injection correction time for cylinders with weak explosion force. Thus, if actual amount of injection in any cylinder does not reach predetermined value, the rotation fluctuation is uniformed. Also, the ECU 30 guards the fuel injection correction time with basic injection time multiplied by a guard factor as a ceiling value. Accordingly, the ceiling value is changed by load to limit the increase and correction of the amount of fuel injection, and some of fuel injection valves 11 may originally have weak explosion force due to bad atomization condition, etc. In this case, however, excessive bad atomization condition caused by a big amount of fuel injection is prevented.

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 system for a multi-cylinder internal combustion engine. The present invention relates to a fuel injection control device for a multi-cylinder internal combustion engine that corrects and controls the amount of fuel injection to be performed.

[0002]

2. Description of the Related Art Conventionally, as this kind of technology, for example, JP-A-61-46444 or JP-A-62-235 is known.
A technique disclosed in Japanese Patent Publication No. 52-52 and the like is known. In these techniques, an engine having a plurality of cylinders is provided with a fuel injection valve corresponding to each cylinder. By the way, such manufacturing variations of the fuel injection valve,
The injection performance may vary from cylinder to cylinder due to a change over time, and the fuel injection amount may vary from cylinder to cylinder. For example, in a certain fuel injection valve, a situation may occur in which the amount of fuel actually injected becomes smaller than the target injection amount (command value). In this case, there is a possibility that the rotation of the engine particularly during idling becomes unstable.

In order to cope with such inconveniences, in the prior art described in these publications, the fuel injection correction amount is set for each cylinder during idling so that the rotational fluctuation (and thus the explosive force) between the cylinders becomes uniform. The fuel injection amount is calculated, and the fuel injection amount is increased and corrected with respect to the basic command value. By performing such control, the amount of fuel actually injected becomes the expected value, so that the above-described problem is suppressed.

[0004]

However, in the above technique, there is a possibility that the following problems may occur. That is, depending on the cylinder, the amount of fuel actually injected has almost no difference from the command value, but there is a case where the explosive power is originally weak due to the poor injection state or atomization state. Even in such a case, in the above-described related art, the increase correction of the fuel injection amount is performed.
However, since the explosive power is originally low in the cylinder, even if the injection amount is corrected, the explosive power cannot be improved even if the injection amount is corrected, and misfire may be caused by injecting extra fuel. was there.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the present invention is to calculate a fuel injection correction amount for each cylinder in order to make rotational fluctuations between cylinders uniform, and to perform an injection based on the correction amount. In a fuel injection control device for a multi-cylinder internal combustion engine, wherein a fuel injection amount to be corrected is controlled, a fuel injection control device for a multi-cylinder internal combustion engine capable of suppressing a misfire due to a correction of the fuel injection amount is increased. To provide.

[0006]

In order to achieve the above object, according to the present invention, during idle operation of a multi-cylinder internal combustion engine having a fuel injection valve for each cylinder, rotation of the internal combustion engine for each cylinder is performed. Rotation state detection means for detecting a state,
An injection correction amount calculation unit that calculates a fuel injection correction amount for each cylinder based on the rotation state detected by the rotation state detection unit to equalize rotational fluctuation between cylinders; and an injection correction amount calculation unit. A fuel injection control device for a multi-cylinder internal combustion engine, comprising: a correction control unit that corrects and controls a fuel injection amount injected from the fuel injection valve based on the calculation result. Detecting means, and changing the upper limit value of the fuel injection correction amount calculated by the injection correction amount calculating means in accordance with the detection result of the operating state detecting means, and restricting the correction of increasing the fuel injection amount. The main point is that a means is provided.

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 increase correction limiting means sets the upper limit value when the load on the internal combustion engine is low. The gist is to make it smaller.

Further, according to the third aspect of the present invention, during idle operation of a multi-cylinder internal combustion engine having a fuel injection valve for each cylinder, a rotational state detecting means for detecting a rotational state of the internal combustion engine for each cylinder; Injection correction amount calculation means for calculating a fuel injection correction amount for each cylinder based on the rotation state detected by the state detection means in order to equalize rotational fluctuation between cylinders, and calculation results of the injection correction amount calculation means. A fuel injection control device for a multi-cylinder internal combustion engine, comprising: a correction control unit that corrects and controls a fuel injection amount injected from the fuel injection valve based on the misfire detection unit that detects misfire of the internal combustion engine; When a misfire is detected by the misfire detection means,
The gist of the invention is to provide an increase correction limiting means for reducing the upper limit of the fuel injection correction amount calculated by the injection correction amount calculating means and for limiting the increase correction of the fuel injection amount.

According to a fourth aspect of the present invention, in the fuel injection control apparatus for a multi-cylinder internal combustion engine according to the third aspect, the misfire detecting means detects misfire for each cylinder. The gist of the increase correction limiting means is to reduce the upper limit value only for the cylinder in which misfire has been detected.

In addition, according to the invention described in claim 5, in the fuel injection control apparatus for a multi-cylinder internal combustion engine according to claim 3 or 4, the increase correction limiting means is provided whenever a misfire is detected. The gist is that the upper limit is gradually reduced.

Further, according to the present invention, during idle operation of a multi-cylinder internal combustion engine having a fuel injection valve for each cylinder, a rotational state detecting means for detecting a rotational state of the internal combustion engine for each cylinder; Injection correction amount calculation means for calculating a fuel injection correction amount for each cylinder, based on the rotation state detected by the state detection means, in order to equalize rotational fluctuation between cylinders,
A fuel injection control device for a multi-cylinder internal combustion engine, comprising: a correction control means for correcting and controlling a fuel injection amount injected from the fuel injection valve based on a calculation result of the injection correction amount calculation means. Misfire detection means for detecting misfire; and when misfire is detected by the misfire detection means, the fuel injection correction amount calculated by the injection correction amount calculation means is reduced to limit the increase correction of the fuel injection amount. In addition, the gist of the present invention is to provide an increase correction restriction stopping means for stopping the updating of the fuel injection correction amount thereafter.

According to a seventh aspect of the present invention, in the fuel injection control device for a multi-cylinder internal combustion engine according to the sixth aspect, the misfire detecting means detects misfire for each cylinder. The gist of the correction restriction stopping means is to reduce the fuel injection correction amount only for the cylinder in which misfire has been detected.

In addition, according to the present invention, during idle operation of a multi-cylinder internal combustion engine having a fuel injection valve for each cylinder, a rotational state detecting means for detecting a rotational state of the internal combustion engine for each cylinder; Injection correction amount calculation means for calculating a fuel injection correction amount for each cylinder based on the rotation state detected by the rotation state detection means to equalize rotational fluctuation between cylinders, and calculation by the injection correction amount calculation means A fuel injection control device for a multi-cylinder internal combustion engine, comprising: a correction control unit that corrects and controls a fuel injection amount injected from the fuel injection valve based on the result; and a misfire detection unit that detects a misfire of the internal combustion engine. When misfire is detected by the misfire detection means, correction control prohibition means for prohibiting correction control of the fuel injection amount based on the calculation result of the injection correction amount calculation means thereafter is provided. Are you as its gist.

In addition, according to the ninth aspect of the present invention, during idle operation of a multi-cylinder internal combustion engine having a fuel injection valve for each cylinder, a rotational state detecting means for detecting a rotational state of the internal combustion engine for each cylinder; Injection correction amount calculation means for calculating a fuel injection correction amount for each cylinder based on the rotation state detected by the rotation state detection means to equalize rotational fluctuation between cylinders, and calculation by the injection correction amount calculation means A fuel injection control device for a multi-cylinder internal combustion engine, comprising: a correction control means for correcting and controlling a fuel injection amount injected from the fuel injection valve based on the result. The gist of the invention is to provide a misfire suppression control means for controlling an actuator different from the fuel injection valve according to the injection correction amount to suppress misfire.

According to a tenth aspect of the present invention, in the fuel injection control device for a multi-cylinder internal combustion engine according to the ninth aspect, the misfire suppression control means controls a plurality of the actuators. It is a gist.

Further, in the fuel injection control apparatus for a multi-cylinder internal combustion engine according to the ninth or tenth aspect of the present invention, the actuator includes an exhaust recirculation control valve for adjusting an exhaust recirculation amount. The gist is that the misfire suppression control means controls at least the exhaust gas recirculation control valve to reduce the amount of exhaust gas recirculation.

(Operation) According to the first aspect of the present invention,
Fuel is individually injected from fuel injection valves provided for each cylinder of the multi-cylinder internal combustion engine. The rotation state detection means detects a rotation state for each cylinder during an idle operation of the internal combustion engine. Further, based on the rotation state detected by the rotation state detection unit, the injection correction amount calculation unit calculates the fuel injection correction amount for each cylinder in order to equalize the rotational fluctuation between the cylinders. The correction control means corrects and controls the fuel injection amount injected from the fuel injection valve based on the calculation result of the injection correction amount calculation means. For this reason, when the actually injected fuel is less than the expected fuel amount, the injection amount is corrected to the increased side, and therefore, the explosive power between the cylinders is made uniform, and the rotation fluctuation is made uniform. You. As a result, the idling speed is stabilized.

According to the present invention, the operating state of the internal combustion engine is detected by the operating state detecting means. Then, in accordance with the detection result, the increase correction limiting means changes the upper limit value of the fuel injection correction amount calculated by the injection correction amount calculating means, thereby limiting the increase correction of the fuel injection amount. For this reason, some fuel injectors may have an inherently weak explosive power due to poor injection or atomization, but in such a case, the correction for increasing the fuel injection amount is limited. Therefore, further deterioration of the atomization state due to injection of more fuel is suppressed, and misfire hardly occurs.

According to a second aspect of the present invention, in addition to the operation of the first aspect, when the load on the internal combustion engine is low, the upper limit value is reduced by the increase correction limiting means. Can be Here, when the load of the internal combustion engine is low, it is common that misfire is likely to occur. In the present invention, since the upper limit value is reduced at such a low load, the above-described action is reliably performed at a low load, and misfire is unlikely to occur.

Further, according to the third aspect of the present invention,
The rotation state detecting means, the injection correction amount calculating means, the correction control means, and the like have the same functions as those described in the function of the first aspect of the present invention. In addition, in the present invention, when misfire is detected by the misfire detection means, the increase correction restriction means reduces the upper limit value of the fuel injection correction amount calculated by the injection correction amount calculation means, thereby reducing the fuel injection amount. Increase correction is limited. Therefore, once misfire is detected, further deterioration of the atomization state and the like are suppressed, and misfire hardly occurs thereafter.

In addition, according to the invention described in claim 4,
In addition to the effect of the third aspect of the invention, misfire is detected for each cylinder by misfire detection means, and the increase correction restriction means reduces the upper limit value only for the cylinder in which misfire is detected. Therefore, for a cylinder in which a misfire has not yet occurred, the upper limit value is maintained at the same value as before, and the increase correction of the fuel injection amount in the cylinder is not unnecessarily limited. For this reason, it is possible to further balance the effect that the misfire hardly occurs and the effect of stabilizing the idle speed.

In addition, according to the fifth aspect of the present invention,
In addition to the effect of the invention described in claims 3 and 4, the increase correction limiting means reduces the upper limit stepwise each time misfire is detected. For this reason, the upper limit value reduced by the increase correction restricting means can be set to a value just before the misfire does not occur (the value immediately before the misfire), and further, the misfire does not easily occur thereafter. Thus, the effects of stabilizing the idling speed can be further improved.

According to the sixth aspect of the present invention, the rotation state detecting means, the injection correction amount calculating means, the correction control means, etc. are the same as those described in the operation of the first aspect of the present invention. The action of is achieved. In addition, according to the present invention, when misfire is detected by the misfire detecting means, the fuel injection correction amount is reduced by the fuel increase correction restriction stopping means, and the fuel injection correction amount is restricted from being increased. , The update of the fuel injection correction amount is stopped. Therefore, once misfire is detected, further deterioration of the atomization state and the like are suppressed, and misfire hardly occurs thereafter. At the same time, the subsequent fuel injection correction amount is not increased, so that re-fire is reliably suppressed.

Further, according to the invention described in claim 7,
In addition to the effect of the invention according to claim 6, a misfire is detected for each cylinder by the misfire detection means, and the fuel injection correction amount is reduced only for the cylinder in which the misfire is detected by the increase correction restriction stop means. Therefore, for a cylinder in which misfire has not yet occurred, the fuel injection correction amount is maintained at the same amount as before, and the increase correction of the fuel injection amount in the cylinder is not unnecessarily limited. for that reason,
Thereafter, it is possible to further achieve both the effect that the misfire hardly occurs and the effect that the idling speed is stabilized.

In addition, according to the invention described in claim 8,
The rotation state detecting means, the injection correction amount calculating means, the correction control means, and the like have the same functions as those described in the function of the first aspect of the present invention. In addition, in the present invention, when misfire is detected by the misfire detection means, the correction control prohibition means prohibits the correction control of the fuel injection amount based on the calculation result of the injection correction amount calculation means thereafter. Therefore, the subsequent misfire is reliably suppressed.

In addition, according to the ninth aspect of the present invention,
The rotation state detecting means, the injection correction amount calculating means, the correction control means, and the like have the same functions as those described in the function of the first aspect of the present invention. In addition, according to the present invention, the actuator other than the fuel injection valve is controlled by the misfire suppression control means in accordance with the fuel injection correction amount calculated by the injection correction amount calculation means, so that the other actuator is controlled by the fuel injection correction amount. A misfire that can occur when the control is performed without considering the correction amount is reliably suppressed.

According to the tenth aspect of the present invention,
In addition to the effect of the ninth aspect, the plurality of actuators are controlled by the misfire suppression control means. Therefore, the above-described operation is more reliably performed, and in some cases, deterioration of exhaust emission is suppressed.

According to the eleventh aspect of the present invention, in addition to the functions of the ninth and tenth aspects, the actuator includes an exhaust gas recirculation control valve for adjusting the amount of exhaust gas recirculation. The misfire suppression control means controls at least the exhaust gas recirculation control valve to reduce the amount of exhaust gas recirculation. Here, the reduction of the exhaust gas recirculation amount is effective in suppressing misfire. Therefore, misfire can be suitably suppressed by the above control.

[0029]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS (First Embodiment) Hereinafter, a fuel injection control device for a multi-cylinder internal combustion engine according to the present invention is embodied as an engine capable of performing not only homogeneous combustion but also stratified combustion. Embodiments will be described in detail with reference to the drawings.

Here, the stratified combustion will be briefly described. In a commonly used engine (homogeneous combustion engine), fuel from a fuel injection valve is injected into an intake port, and a homogeneous mixture of fuel and air is supplied to a combustion chamber in advance. In such an engine, an intake passage is opened and closed by a throttle valve interlocked with accelerator operation, and by this opening and closing, the amount of intake air supplied to the combustion chamber (as a result, the amount of gas in which fuel and air are homogeneously mixed). Is adjusted, so that the engine output is controlled.

However, in the technique based on the so-called homogeneous combustion described above, a large intake negative pressure is generated with the throttle operation of the throttle valve, and the pumping loss increases to lower the efficiency. On the other hand, by reducing the throttle of the throttle valve and supplying fuel directly to the combustion chamber, a combustible mixture is present in the vicinity of the ignition plug, the concentration of the mixture is increased in the portion, and the ignitability is improved. Such a technique called so-called stratified combustion is known. In this technology, for example, when the engine is under a low load, fuel from a fuel injection valve is directly injected into a combustion chamber, is unevenly supplied around a spark plug, and a throttle valve is opened to perform stratified combustion. You. As a result, the pumping loss is reduced, and the fuel efficiency is improved.

FIG. 1 is a schematic configuration diagram showing a fuel injection control device for a multi-cylinder stratified combustion engine mounted on a vehicle in the present embodiment. The engine 1 has, for example, four cylinders 1a, and the combustion chamber structure of each of the cylinders 1a is shown in FIG. As shown in these figures, the engine 1 has a piston in a cylinder block 2,
The piston reciprocates in the cylinder block 2.
A cylinder head 4 is provided above the cylinder block 2, and a combustion chamber 5 is formed between the piston and the cylinder head 4. Further, in the present embodiment, four valves are arranged per cylinder 1a, and in the figure, the first intake valve 6a, the second intake valve 6b, the first intake port 7a, and the first intake port 7b in the figure. Two intake ports, a pair of exhaust valves as 8, and a pair of exhaust ports as 9 are shown.

As shown in FIG. 2, the first intake port 7a
Is composed of a helical intake port, and the second intake port 7
b consists of a straight port extending almost straight.
In addition, an ignition plug 10 is disposed at the center of the inner wall surface of the cylinder head 4. This spark plug 10 includes:
A high voltage from the ignition coil is applied via a distributor (not shown). The ignition timing of the ignition plug 10 is determined by the output timing of the ignition signal from the igniter 12. Further, a fuel injection valve 11 is disposed around the inner wall surface of the cylinder head 4 near the first intake valve 6a and the second intake valve 6b. That is, in the present embodiment, the fuel from the fuel injection valve 11 is directly injected into the cylinder 1a, so that not only so-called homogeneous combustion but also stratified combustion is performed. .

As shown in FIG. 1, a first intake port 7a and a second intake port 7b of each cylinder 1a are respectively connected via a first intake passage 15a and a second intake passage 15b formed in each intake manifold 15. Connected to the surge tank 16. A swirl control valve 17 is arranged in each second intake passage 15b. These swirl control valves 17 share a common shaft 1
For example, it is connected to a stepping motor 19 via the motor 8. The step motor 19 is controlled based on an output signal from an electronic control unit (hereinafter simply referred to as “ECU”) 30 described later. Instead of the swirl control valve 17 driven by the step motor 19, a valve controlled according to the negative pressure of the intake ports 7a and 7b of the engine 1 may be used.

The surge tank 16 includes an intake duct 20
Is connected to the air cleaner 21 through the intake duct 20.
Inside, a throttle valve 23 which is opened and closed by a step motor 22 is provided. That is, the throttle valve 23 of the present embodiment is of a so-called electronic control type. Basically, the throttle valve 23 is driven by the step motor 22 as an actuator based on the output signal from the ECU 30. 23 is controlled to open and close. By opening and closing the throttle valve 23, the amount of intake air introduced into the combustion chamber 5 through the intake duct 20 is adjusted.

In the vicinity of the throttle valve 23, a throttle sensor 25 for detecting the opening (throttle opening TA) is provided. An exhaust manifold 14 is connected to the exhaust port 9 of each cylinder.
The exhaust gas after combustion is discharged to an exhaust pipe (not shown) through the exhaust manifold 14.

Further, in this embodiment, a known exhaust gas recirculation (EGR) mechanism 51 is provided. This E
The GR mechanism 51 includes an EGR passage 52 as an exhaust gas recirculation passage, and an EGR valve 53 provided in the middle of the EGR passage 52. The EGR passage 52 is provided so as to communicate between the intake duct 20 downstream of the throttle valve 23 and the exhaust duct. Also, the EGR valve 53
Has a built-in valve seat, valve body, and step motor (all not shown). The opening degree of the EGR valve 53 fluctuates when the stepping motor intermittently displaces the valve body with respect to the valve seat. When the EGR valve 53 opens, a part of the exhaust gas discharged to the exhaust pipe becomes EG.
It flows to the R passage 52. The exhaust gas flows to the intake duct 20 via the EGR valve 53. That is, a part of the exhaust gas is recirculated into the intake air-fuel mixture by the EGR mechanism 51. At this time, the recirculation amount of the exhaust gas is adjusted by adjusting the opening degree of the EGR valve 53.

The above-described ECU 30 is formed of a digital computer, and is connected to a random access memory (RAM) 3 via a bidirectional bus 31.
2, a ROM (Read Only Memory) 33, a CPU (Central Processing Unit) 34 composed of a microprocessor, an input port 35 and an output port 36.

An accelerator sensor 26A for generating an output voltage proportional to the amount of depression of the accelerator pedal 24 is connected to the accelerator pedal 24.
Accelerator opening ACCP is detected by 6A. The output voltage of the accelerator sensor 26A is input to the input port 35 via the AD converter 37. Similarly, the accelerator pedal 24 has a fully-closed switch 26B for detecting that the depression amount of the accelerator pedal 24 is "0".
Is provided. That is, the fully closed switch 26B
Generates a signal of “1” as the fully closed signal XIDL when the depression amount of the accelerator pedal 24 is “0”, and generates a signal of “0” otherwise. The output voltage of the fully closed switch 26B is also input to the input port 35.

The top dead center sensor 27 generates an output pulse when the first cylinder 1a reaches the intake top dead center, for example.
This output pulse is input to the input port 35. The crank angle sensor 28 has a crankshaft of 30 ° C.
An output pulse is generated every time the A rotation is performed, and the output pulse is input to the input port. The CPU 34 calculates (reads) the engine speed NE and the like from the output pulse of the top dead center sensor 27 and the output pulse of the crank angle sensor 28.

Further, the rotation angle of the shaft 18 is detected by a swirl control valve sensor 29,
As a result, the opening degree of the swirl control valve 17 (S
CV opening DSCV) is measured. The output of the swirl control valve sensor 29 is output from the A / D converter 37.
Through the input port 35.

At the same time, the throttle sensor 25 detects the throttle opening degree TA. The output of the throttle sensor 25 is input to an input port 35 via an A / D converter 37.

In addition, in the present embodiment, the intake pressure sensor 6 for detecting the pressure (intake pressure) PM in the surge tank 16
1 is provided. Further, in the present embodiment, a water temperature sensor 62 for detecting the temperature (cooling water temperature) THW of the cooling water of the engine 1 is provided. In addition, a vehicle speed sensor 63 for detecting a vehicle speed (vehicle speed) SPD is also provided. And, each of these sensors 61, 62, 63
Is also input to the input port 35 via the A / D converter 37.

On the other hand, the output port 36 is connected to each fuel injection valve 11 and each step motor 1 via the corresponding drive circuit 38.
9, 22, the igniter 12 and the EGR valve 53 (step motor). Then, the ECU 30 operates according to a control program stored in the ROM 33 based on signals from the sensors 25 to 29 and 61 to 63 and the like.
The fuel injection valve 11, the step motors 19 and 22, the igniter 12, the EGR valve 53 and the like are suitably controlled.

Next, the multi-cylinder engine 1 having the above configuration
A program related to various controls according to the present embodiment in the fuel injection control device will be described with reference to flowcharts and the like. That is, FIG. 3 shows a “correction amount calculation routine” for calculating the idling stabilization correction amount KIDL2 used for calculating the fuel injection amount (fuel injection time) when controlling the fuel injection valve 11 in the present embodiment. It is a flowchart which shows. Here, the idling stabilization correction amount KIDL2 is a value added to the basic injection time TAUC when calculating the fuel injection time. This routine is executed by the ECU at each top dead center (TDC) interrupt.
30 is performed.

When the processing shifts to this routine, the ECU
First, in step 101, each sensor 25 to 30
The detection signals from 29, 61 to 63 are read. Next, E
In step 102, the CU 30 determines whether or not the execution condition of the idling stabilization correction control is satisfied based on the currently read signal. Such execution conditions include, for example, after starting, that the fully-closed signal XIDL is “1” (idle state), and that the engine speed NE is within a predetermined range (for example, 525 r
pm ≦ NE ≦ 1000 rpm), that the cooling water temperature THW is equal to or higher than a predetermined temperature (for example, THW ≧ 75 ° C.), and that there is no load change, for example, that the air conditioner switch has not been switched. If the execution condition is satisfied, the ECU 30 proceeds to step 103 and executes the current TDC
An inter-cylinder explosion deviation time DSTM [n], which is a deviation time between the required time of the section and the required time of the previous TDC section, is calculated. Here, [n] means that the n-th cylinder corresponds to the explosion (explosion stroke) in the current TDC section, and the inter-cylinder explosion deviation time DSTM [n] corresponds to the corresponding cylinder 1a. It is calculated every time, and is calculated by smoothing (gradually changing) the current cylinder-to-cylinder explosion deviation time from the previous value.

Subsequently, in step 104, the ECU 30 determines whether or not a misfire has actually occurred. Here, whether or not a misfire has occurred is determined based on the inter-cylinder explosion deviation time this time (before the smoothing operation is performed).
That is, when the current cylinder-to-cylinder explosion deviation time is longer than the predetermined time, it is determined that the inter-cylinder explosion deviation time is long because the corresponding n-th cylinder is misfired, It will be determined that a misfire has occurred.

If no misfire has occurred,
Move to step 105. In step 105,
The ECU 30 calculates the inter-cylinder explosion deviation time D during the last 16 revolutions.
Recognize the cylinder 1a having the maximum value of STM [n] (this cylinder is referred to as cylinder n1).

In the next step 106, the fuel injection correction time TICYL for the cylinder n1 is set.
[N] is increased. That is, a value obtained by adding the predetermined amount PBINC to the fuel injection correction time TICYL [n] up to that time is used as a new fuel injection correction time TICYL.
Set as [n].

Further, in step 107, the fuel injection correction time TICYL1 for the first to fourth cylinders
It is confirmed whether or not any one of .about.TICYL4 is "0". When any one of the fuel injection correction times TICY1 to TICY4 of the first to fourth cylinders is “0”, it can be confirmed that at least one of the cylinders is the reference. If so, the process jumps to step 109. In contrast, 1
Fuel injection correction time TIYL from cylinder # 4 to cylinder # 4
If none of 1 to TICYL4 is “0”, in step 108, all cylinders 1a
, The fuel injection correction time TIYL [n] is reduced. That is, the previous fuel injection correction time TICY
A value obtained by subtracting a predetermined amount PBINC from L [n] is set as a new fuel injection correction time TICYL [n].
As a result, any one of the fuel injection correction times TICY1 to TICY4 of the first to fourth cylinders becomes “0”, so that at least one of the cylinders can be used as a reference.

Now, step 107 or step 108
In step 109, the ECU 30
Indicates that the fuel injection correction time TIYL [n] is greater than or equal to “0” and the basic injection time TAUC is equal to the guard coefficient GLID.
Guarding is performed so as to be equal to or less than the value obtained by multiplying LMX. That is, if the fuel injection correction time TICY [n] is a negative value, “0” is set to the fuel injection correction time TICY [n].
And the basic injection time TAU
If C is larger than the value obtained by multiplying the guard coefficient GLIDLMX by the guard coefficient G
The value multiplied by LIDLMX is used as a fuel injection correction time TIC.
YL [n] is forcibly set.

Then, in the following step 110, E
The CU 30 calculates the currently set fuel injection correction time TI
CYL [n] is replaced with the final idle stabilization correction amount KID.
L2 [n], and the subsequent processing ends once.

On the other hand, if it is determined in step 104 that a misfire has occurred, the process proceeds to step 111. Then, in step 111, EC
U30 decreases the fuel injection correction time TTICL [n] for the cylinder 1a in which the misfire has occurred. That is, a value obtained by subtracting the predetermined amount PBINC from the previous fuel injection correction time TICYL [n] is set as a new fuel injection correction time TICYL [n]. Then E
The CU 30 executes the processing of steps 109 and 110.
As a result, the fuel injection correction time TICYL [n] becomes a small value, so that a further misfire hardly occurs due to a further increase in the fuel injection amount.

If it is determined in step 102 that the condition for executing the correction control for idling stabilization is not satisfied, then in step 112, the current fully closed signal XIDL is set.
Is determined to be “0”. And the fully closed signal X
If the IDL is "1", it is determined that the current state is the idle state, and the subsequent processing is temporarily terminated without performing any processing. On the other hand, the fully closed signal XIDL is "0".
In the case of, it is determined that the engine is not currently in the idle state, and in step 113, the idling stabilization correction amounts KIDL2 [n] are cleared to "0" for all the cylinders 1a.
Thereafter, the processing is temporarily terminated.

Next, the operation and effect of this embodiment will be described. According to the present embodiment, for the cylinder n1 having the maximum value of the inter-cylinder explosion deviation time DSTM [n] during the last 16 rotations, the fuel injection correction time TIXL [n] is increased and corrected. Id stabilization correction amount KI based on
DL2 [n] was determined. Therefore, when there is a cylinder (cylinder n1) in which the fuel actually injected does not reach the scheduled fuel amount, the cylinder n1
Will be corrected to the increase side. Therefore, the explosive force between the cylinders 1a is made uniform, and the rotation fluctuation is made uniform. As a result, the idling speed can be stabilized.

In the present embodiment, the guard is applied to the fuel injection correction time TICYL [n]. In particular, in the present embodiment, the value obtained by multiplying the basic injection time TAUC by the guard coefficient GLIDLMX is set as the upper limit value. For this reason, the upper limit value is changed according to the basic injection time TAUC, so that the increase correction of the fuel injection amount is limited. Therefore, some of the fuel injection valves 11 include
In some cases, the explosive power is originally weak due to poor injection or atomization conditions.In such cases, however, more fuel is injected because the correction for increasing the injection amount is limited. This further suppresses the deterioration of the atomization state and the like. As a result, misfire can be effectively suppressed.

Further, the basic injection time TA as a load
Since the upper limit value is changed according to UC, when the load on engine 1 is low, the upper limit value is reduced. Here, when the load of the engine 1 is low, it is common that misfire is likely to occur. In the present embodiment, since the upper limit value is reduced at such a low load, the above-described operation and effect are surely achieved at a low load, and as a result, misfire can be suppressed more efficiently.

(Second Embodiment) Next, a second embodiment of the present invention will be described. However, in the configuration and the like of the present embodiment, the same reference numerals are given to members and the like that are the same as those of the above-described first embodiment, and description thereof will be omitted. The following description focuses on the differences from the first embodiment.

In the first embodiment, step 10
7, 108, 111, the fuel injection correction time T
When guarding ICYL [n] (step 10
9) The guard coefficient GLIDLM is added to the basic injection time TAUC.
The value obtained by multiplying X was set as the upper limit. On the other hand, the present embodiment has a feature in the method of setting the upper limit.

FIG. 4 is a flowchart showing a part of a "correction amount calculation routine" for calculating the idling stabilization correction amount KIDL2. The ECU 30 executes the processing of steps 101 to 108 and the processing of steps 111, 112, and 113 described in the first embodiment. And the ECU 30
After the processing in step 108 or in step 1
If the result of the determination in step 07 is affirmative, or after the process of step 111, the process proceeds to step 201. In step 201, the upper limit value C is determined by referring to a predetermined map based on the detection signal and the like read this time.
Calculate YLMX. Here, the predetermined map is used for combustion such as engine speed NE, basic injection time TAUC (corresponding to load), cooling water temperature THW, SCV opening DSCV, required EGR opening, throttle opening TA, purge amount, and the like. Depending on each controlling factor or its combination,
It is predetermined.

Further, the ECU 30 executes the following step 202
, The fuel injection correction time TIXL [n] is
Guarding is performed so as to be equal to or more than "0" and equal to or less than the upper limit value CYLMX. That is, the fuel injection correction time TIC
If YL [n] is a negative value, “0” is forcibly set as the fuel injection correction time TIXL [n], and if larger than the upper limit CYLMX, the upper limit CYLMX is set to It is compulsorily set as the correction time TIXL [n].

Then, in the following step 110, E
The CU 30 calculates the currently set fuel injection correction time TI
CYL [n] is replaced with the final idle stabilization correction amount KID.
L2 [n], and the subsequent processing ends once.

As described above, in the present embodiment, the upper limit value CYLMX is set by considering the map in consideration of not only the engine load (basic injection time TAUC) but also other operating conditions. . Therefore, the upper limit value CYLMX can be set to a more optimal value, and the operation and effect described in the first embodiment can be more reliably achieved.

(Third Embodiment) Next, a third embodiment of the present invention will be described. However, also in the configuration and the like of the present embodiment, the same reference numerals are given to members and the like that are the same as those of the above-described first embodiment, and description thereof will be omitted. The following description focuses on the differences from the first embodiment.

In the first embodiment, step 10
4, it is determined that a misfire has occurred. For the cylinder 1a in which the misfire has occurred, a value obtained by subtracting a predetermined amount PBINC from the fuel injection correction time TICYL [n] up to that time is used as a new fuel injection. Correction time TICYL
[N]. On the other hand, in this embodiment, when it is determined that a misfire has occurred,
The fuel injection correction time TICYL [n] is not the upper limit CY
The feature is that LMX [n] is changed.

FIG. 5 is a flowchart showing a part of a "correction amount calculation routine" for calculating the idling stabilization correction amount KIDL2. After executing the processing in step 103 described in the first embodiment, the ECU 30 determines in step 301 whether a misfire has actually occurred. Here, whether or not a misfire has occurred is determined based on the current inter-cylinder explosion deviation time as in the above case. And if no misfire has occurred,
In step 302, the ECU 30 recognizes the cylinder 1a that takes the maximum value of the inter-cylinder explosion deviation time DSTM [n] during the last 16 rotations (this cylinder is referred to as a cylinder n1).

In the next step 303, the fuel injection correction time TICYL for the cylinder n1 is set.
[N] is increased. That is, a value obtained by adding the predetermined amount PBINC to the fuel injection correction time TICYL [n] up to that time is used as a new fuel injection correction time TICYL.
Set as [n].

Further, in step 304, the fuel injection correction time TICYL1 for the first to fourth cylinders
It is confirmed whether or not any one of .about.TICYL4 is "0". When any one of the fuel injection correction times TICY1 to TICY4 of the first to fourth cylinders is “0”, it can be confirmed that at least one of the cylinders is the reference. Then, the process jumps to step 306. In contrast, 1
Fuel injection correction time TIYL from cylinder # 4 to cylinder # 4
If none of 1 to TICYL4 is “0”, in step 305, all the cylinders 1a
, The fuel injection correction time TIYL [n] is reduced. That is, the previous fuel injection correction time TICY
A value obtained by subtracting a predetermined amount PBINC from L [n] is set as a new fuel injection correction time TICYL [n].

Now, step 304 or step 305
In step 306, the ECU 30
Guards the fuel injection correction time TIXL [n] to be equal to or more than “0” and equal to or less than the upper limit value CYLMX [n]. That is, the fuel injection correction time TIXL
If [n] is a negative value, “0” is forcibly set as the fuel injection correction time TIXL [n], and if it is larger than the upper limit CYLMX [n], the upper limit CYLMX [ n] is the fuel injection correction time TIXL
[N] is forcibly set.

Then, in the following step 110, E
The CU 30 calculates the currently set fuel injection correction time TI
CYL [n] is replaced with the final idle stabilization correction amount KID.
L2 [n], and the subsequent processing ends once.

On the other hand, if it is determined in step 301 that a misfire has occurred, the process proceeds to step 307. Then, in step 307, the EC
U30 decreases the upper limit value CYLMX [n] for the cylinder 1a in which the misfire has occurred. That is, the predetermined amount PBD is increased with respect to the upper limit value CYLMX [n].
The value obtained by subtracting the EC is set as a new upper limit value CYLMX [n]. Thereafter, the ECU 30 proceeds to step 306,
Step 110 is executed. Note that the upper limit value CYLMX
As the initial value of [n], an empirical value is set in advance as a limit value that can limit an excessive increase in the fuel injection amount for a cylinder with a poor injection state or atomization state while guaranteeing stabilization of the idle speed. Is used.

As described above, according to the present embodiment, when a misfire is detected, the upper limit value CYLMX [n] is set to a small value, and the increase correction of the fuel injection amount is further restricted from the next time onward. It will be. Therefore, once misfire is detected, further deterioration of the atomization state or the like is suppressed, and misfire can be suppressed thereafter.

In this embodiment, misfire is detected for each cylinder 1a, and the upper limit value CYLMX [n] is reduced only for the cylinder 1a in which the misfire is detected. Therefore, for the cylinder 1a in which misfire has not yet occurred, the upper limit value CYLMX [n] is maintained at the same value as before, and the fuel increase correction in the cylinder 1a is unnecessarily limited. There is no. for that reason,
Since then, the effect of being able to suppress misfire, and
It is possible to further stabilize the idling rotational speed, and to further achieve the operational effect.

Further, in the present embodiment, the upper limit value CYLMX [n] is reduced stepwise each time a misfire is detected. For this reason, the upper limit value CYLMX [n] immediately after step 307 can be a marginal value (a value immediately before misfire) that does not cause misfire, and furthermore, the misfire is less likely to occur thereafter. Thus, it is possible to further achieve both the effect and the effect of stabilizing the idle speed.

(Fourth Embodiment) Next, a fourth embodiment of the present invention will be described. However, also in the configuration and the like of the present embodiment, the same reference numerals are given to members and the like that are the same as those of the above-described first embodiment, and description thereof will be omitted. The following description focuses on the differences from the first embodiment.

In the first embodiment, even if it is determined in step 104 that misfire has occurred, if the predetermined requirement is satisfied, then the increase correction control is executed. In contrast, in the present embodiment,
It is characterized in that once it is determined that a misfire has occurred, the increase correction control is stopped thereafter.

FIG. 6 is a flowchart showing a "correction amount calculation routine" for calculating the idling stabilization correction amount KIDL2 (however, the signal reading process is omitted for convenience).

When the processing shifts to this routine, the ECU
30 first determines in step 401 whether the idling misfire occurrence flag XIDLMS is "1". Here, the idle misfire occurrence flag XIDLMS is set to “0” when no misfire has occurred, and is set to “1” once misfire has been detected.
(See step 414 described later). When the idle misfire occurrence flag XIDLMS is set to “0”, the process proceeds to step 402.

In step 402, the ECU 30
Based on the signal read this time, it is determined whether or not the execution condition of the idle stabilization correction control is satisfied. Then, if the execution condition is satisfied, the ECU 30 proceeds to step 403 and executes the inter-cylinder explosion deviation time DSTM.
[N] is calculated.

Subsequently, in step 404, the ECU 30 determines whether or not a misfire has actually occurred. If no misfire has occurred, step 405 is performed.
And the cylinder explosion deviation time DST during the last 16 revolutions
The cylinder 1a that takes the maximum value of M [n] (the cylinder
). Further, in the next step 406, the fuel injection correction time TTICL [n] is increased and corrected for the cylinder n1. That is, a value obtained by adding the predetermined amount PBINC to the previous fuel injection correction time TICYL [n] is set as a new fuel injection correction time TICYL [n].

Further, in step 407, the fuel injection correction time TICYL1 for the first to fourth cylinders
It is confirmed whether or not any one of .about.TICYL4 is "0". If any one of the fuel injection correction times TICY1 to TICY4 of the first to fourth cylinders is “0”, it can be confirmed that one of the cylinders is the reference. To step 409. On the other hand, the fuel injection correction times TICYL1 to TICYL for the first to fourth cylinders
If none of YL4 is "0", in step 408, the fuel injection correction time TICYL [n] is reduced for all cylinders 1a. That is, the previous fuel injection correction time TIXL [n]
, A value obtained by subtracting the predetermined amount PBINC is set as a new fuel injection correction time TTICL [n].

Now, step 407 or step 408
In step 409, the ECU 30
Guards the fuel injection correction time TIYL [n] to be equal to or greater than “0” and equal to or less than the upper limit α. That is, if the fuel injection correction time TICY [n] is a negative value, “0” is set to the fuel injection correction time TICY [n].
And when it is larger than the upper limit value α, the upper limit value α is set to the fuel injection correction time TIXL
[N] is forcibly set. Here, the upper limit α is
It may be a predetermined value or a variable value.

In the following step 410, E
The CU 30 calculates the currently set fuel injection correction time TI
CYL [n] is replaced with the final idle stabilization correction amount KID.
L2 [n], and the subsequent processing ends once.

If the idle misfire occurrence flag XIDLMS is "1" in step 401, that is, if the occurrence of misfire is detected once, or if the execution condition of the idle stabilization correction control is determined in step 402, If not, step 41
At 1, it is determined whether or not the currently fully closed signal XIDL is “0”. When the fully-closed signal XIDL is “1”, it is determined that the current state is the idle state, and the subsequent processing is temporarily terminated without performing any processing. On the other hand, when the fully-closed signal XIDL is “0”, it is determined that the vehicle is not in the idle state at present, the idle misfire occurrence flag XIDLMS is reset to “0” in step 412, and all the Idle stabilization correction amount KIDL2 for cylinder 1a
[N] is cleared to "0", and the subsequent processing ends once.

On the other hand, if it is determined in step 404 that a misfire has occurred, the process proceeds to step 414. Then, in this step 414, the idle misfire occurrence flag XIDLMS is set to "1".
Thereafter, in step 415, the ECU 30 sets the fuel injection correction time TTICL [n] of the cylinder in which the misfire has occurred to “0”, and then executes the processing in steps 409 and 410.

As described above, according to the present embodiment, the occurrence of misfire is detected once, and the idling misfire occurrence flag XIDL
If the MS is "1", the fuel injection correction amount (fuel injection correction time TICYL [n]) is set in step 411, provided that the fully closed signal XIDL is "1", that is, the engine is currently in an idle state. Update is stopped. Therefore, once the misfire is once detected, further deterioration of the atomization state or the like is suppressed, and the misfire hardly occurs thereafter. At the same time, since the fuel injection correction amount is not increased thereafter, it is possible to reliably suppress the occurrence of the second misfire.

Further, according to the present embodiment, even if it is determined that a misfire has occurred once, after that, in step 411, the fully closed signal XIDL is set to "0", that is, the non-idle state. When it is determined, the idle misfire occurrence flag XIDLMS is reset to “0”. For this reason, if the cause of the misfire is removed for some reason during traveling, the increase correction can be performed again. As a result, the idling speed can be further stabilized.

Further, according to the present embodiment, the cylinder 1a
Each time a misfire is detected, the fuel injection correction amount (fuel injection correction time TICYL) is determined only for the cylinder 1a where the misfire is detected.
[N]) was set to “0”. Therefore, for the cylinder 1a in which a misfire has not yet occurred, the fuel injection correction amount is maintained at the same amount as before, and the fuel increase correction in the cylinder 1a is not unnecessarily limited. Therefore, as in the third embodiment, it is possible to further achieve both the effect of suppressing misfire and the effect of stabilizing the idle speed.

(Fifth Embodiment) Next, a fifth embodiment of the present invention will be described. However, also in the configuration and the like of the present embodiment, the same reference numerals are given to members and the like that are the same as those of the above-described embodiments, and description thereof will be omitted. The following description focuses on differences from the fourth embodiment.

In the fourth embodiment, when it is determined that a misfire has occurred once, the increase correction control is stopped thereafter. On the other hand, in the present embodiment, once it is determined that misfire has occurred, the correction control of the fuel injection amount based on the “correction amount calculation routine” is positively prohibited. Even if it is determined that a misfire has occurred once, when it is subsequently determined that the vehicle is in the non-idle state, the idle misfire occurrence flag XIDL
MS is reset to "0" and all cylinders 1a are reset.
In the present embodiment, the idling stabilization correction amount KIDL2 [n] is cleared to “0”.

FIG. 7 is a flowchart showing a "correction amount calculation routine" for calculating the idling stabilization correction amount KIDL2 in the present embodiment (signal reading processing is omitted). However, in the routine shown in FIG. 7, steps for executing the same processing as the “correction amount calculation routine” of the fourth embodiment illustrated in FIG. 6 are denoted by the same step numbers. Here, here, steps 515 and 51, which are processes unique to the present embodiment, are described.
Only the processing according to No. 6 will be described.

That is, in the "correction amount calculation routine" of this embodiment, if it is determined in step 404 that misfire has occurred, in step 414, the idle misfire occurrence flag XIDLMS is set to "1". After that, in step 515, the fuel injection correction time TTICL [n] of the cylinder in which the misfire has occurred is reduced and corrected. That is, the previous fuel injection correction time TICY of the cylinder
A value obtained by subtracting a predetermined amount PBINC from L [n] is set as a new fuel injection correction time TICYL [n]. After that, the processing of the steps 409 and 410 is executed.

As described above, the fuel injection correction time TTICL [n] of the misfire generating cylinder is not necessarily set to “0”, and even if the fuel loss correction correction is performed as in the present embodiment, the subsequent misfire occurs. It will be suppressed suitably.

On the other hand, in the "correction amount calculation routine" of the present embodiment, when the idling misfire occurrence flag XIDLMS is "1" in step 401,
That is, when the occurrence of misfire is detected once, in step 516, the idling stabilization correction amount KIDL2 [n] is cleared to "0" for all cylinders 1a,
That is, after performing the correction control of the fuel injection amount based on the “correction amount calculation routine”, the idling determination of step 411 (“0” or “1” determination of the fully closed signal XIDL) is performed. If the fully closed signal XIDL is "1" in step 411, it is determined that the signal is currently in the idle state, and the subsequent processing is temporarily terminated without performing any processing. Further, the fully closed signal XIDL is “0”.
In step 412, the idle misfire occurrence flag XIDL
MS is reset to “0”, and step 413 is executed.
In step (1), the idling stabilization correction amounts KIDL2 [n] are cleared to "0" for all cylinders 1a, and the subsequent processing is temporarily terminated.

As described above, when the misfire is detected once and the idling misfire occurrence flag XIDLMS is "1", the correction control of the fuel injection amount is prohibited even after the misfire is detected. In this case, further deterioration of the atomization state or the like is suppressed, and a misfire hardly occurs thereafter. At the same time, the fuel injection correction amount is not increased thereafter, so that the occurrence of a second misfire can be reliably suppressed.

Further, similarly to the fourth embodiment, even if it is determined that a misfire has once occurred, the fully closed signal XIDL is set to "0" in step 411, that is, the non-idle state is reached. When it is determined that the misfire has occurred, the idle misfire occurrence flag XIDLMS is reset to "0" to ensure that the increase correction control is executed again when the cause of the misfire has been removed during driving. As a result, the idling speed can be further stabilized.

(Sixth Embodiment) Next, a sixth embodiment of the present invention will be described. Also in this embodiment, differences from the above-described embodiments, particularly differences from the first embodiment, will be mainly described.

In the first embodiment, only the control for increasing the fuel injection amount is considered. On the other hand, the present embodiment is characterized in that control of other actuators (the EGR valve 53 in the present embodiment) is also considered.

FIG. 8 is a flowchart showing a part of a "correction amount calculation routine" for calculating the idling stabilization correction amount KIDL2. In the present embodiment,
As in the first embodiment, the processes of steps 101 to 110 and the processes of steps 111, 112 and 113 are executed. Then, after the processing of step 110, step 112 or step 113, the ECU 30 proceeds to step 601.

At step 601, the ECU 30
The idling stabilization correction amount KIDL2 [n] for each cylinder 1a that is currently set is averaged for all cylinders 1a, and a map (not shown) is referred to based on the calculated average value. , The EGR correction closing amount EGRDEC is calculated.

Then, in the following step 602,
The value obtained by subtracting the EGR correction closing amount EGRDEC calculated this time from the currently set basic EGR opening BEGR (set based on the basic injection time TAUC or the like in a separate routine) is used as the final EGR opening. EGR
Set as REQ. Then, the ECU 30 once ends the subsequent processing.

As described above, according to the present embodiment, in addition to the functions and effects of the first embodiment, the EGR valve 53 which is an actuator separate from the fuel injection valve 11 is provided.
Is the EGR correction closing amount EGRDEC calculated based on the average value of the idling stabilization correction amount KIDL2 [n].
Is taken into account and controlled. Therefore, compared with the case where the final EGR opening degree EGRREQ is set without considering the idling stabilization correction amount KIDL2 [n] at all (in this case, it is set based only on the basic injection time TAUC or the like). Therefore, misfire can be more reliably suppressed.

In this embodiment, the final EGR opening degree EGR is determined according to the idling stabilization correction amount KIDL2 [n].
REQ is corrected to the decreasing side, and the EGR amount is reduced. Here, since the reduction of the EGR amount is effective in suppressing misfire, misfire is more appropriately suppressed by the above-described control.

The present invention is not limited to the above-described embodiments at all, and may be implemented as follows, for example, by appropriately changing a part of the configuration and the like. (1) In the sixth embodiment, apart from the fuel injection valve 11, the EGR valve 53 is also controlled in consideration of the idling stabilization correction amount KIDL2 [n]. On the other hand, other actuators can be similarly controlled.

For example, FIG. 9 is a flowchart showing a part of a "correction amount calculation routine" for calculating the idling stabilization correction amount KIDL2, similarly to the sixth embodiment. Also in the present embodiment, the processes of steps 101 to 110 and the processes of steps 111, 112 and 113 are executed in the same manner as in the sixth embodiment. Then, Step 110 and Step 112
Alternatively, after the processing of step 113, the ECU 30 proceeds to step 701.

In step 701, the ECU 30
The currently set idling stabilization correction amount KIDL2 [n] for each cylinder 1a is averaged for all cylinders 1a, and the total injection is calculated based on the calculated average value, basic injection time TAUC, and the like. Calculate time, and
By converting this into an injection amount, the corrected total injection amount Q
Calculate ALLINJ.

Then, in the following step 702,
Based on the currently set corrected total injection amount QALLINJ, target values of various actuators are calculated. Here, as the target values of the various actuators, for example, in addition to the final EGR opening degree EGRREQ, a target throttle opening degree, a target swirl control valve opening degree, a target ignition timing and the like can be mentioned. Then, the ECU 30 once ends the subsequent processing.

As described above, the misfire can be further suppressed by controlling the other actuators in consideration of the idling stabilization correction amount KIDL2 [n]. Further, in some cases, the effect of suppressing the deterioration of the exhaust emission can be obtained.

(2) In the fourth embodiment, when it is detected that a misfire has occurred, the idle misfire occurrence flag XIDLMS is set to "1" and the fuel injection of the misfire occurrence cylinder is performed. Although the correction time TIXL [n] is set to “0”, in addition to the above processing (immediately after step 415), a processing of subtracting a predetermined amount of the upper limit α (corresponding to the processing of step 307 in FIG. 5) ) May be performed.

By performing such control, the fuel injection correction time TICYL [n] is more likely to be guarded, and the idling stabilization correction amount KIDL2 [n] is stopped during the routine. Can be. As a result, it is possible to further suppress misfire.

(3) In the first to sixth embodiments, misfire is determined when the inter-cylinder explosion deviation time is longer than a predetermined value. However, the inter-cylinder explosion deviation time is determined twice or more continuously. A misfire may be detected only when it is determined that the misfire is longer than the predetermined value, or a misfire may be detected according to the frequency at which the inter-cylinder explosion deviation time is determined to be longer than a predetermined value. Good.

(4) In the first to sixth embodiments, the misfire is detected based on the inter-cylinder explosion deviation time. However, the present invention is not limited to this. Misfire may be detected based on the presence or absence of an ion current flowing therebetween.

(5) In the fourth embodiment, when the fuel injection correction time of the cylinder in which a misfire has occurred is reduced and corrected,
Although the fuel injection correction time is set to “0”, a predetermined amount capable of suppressing misfire may be reduced from the fuel injection correction time.

(6) In each of the above embodiments, the present invention is embodied in the in-cylinder injection type engine 1; It may be. For example, the intake ports 7a, 7
The type which injects toward the back side of the umbrella part of the intake valves 6a and 6b of b is also included. Although a fuel injection valve is provided on the intake valves 6a and 6b side, a type in which fuel is injected directly into the cylinder bore (combustion chamber 5) is also included. Further, the present invention may be embodied in a type of engine that does not perform stratified combustion.

(7) In each of the above-described embodiments, the helical intake port is provided so that a so-called swirl can be generated. However, the swirl need not always be generated. Therefore, for example, the swirl control valve 17, the step motor 19, and the like in the above embodiment can be omitted.

(8) Further, in each of the above embodiments, the present invention has been embodied in the case of the gasoline engine 1 as the internal combustion engine. However, the present invention can also be embodied in the case of a diesel engine or the like.

[0117]

As described in detail above, according to the present invention,
In a fuel injection control device for a multi-cylinder internal combustion engine, a fuel injection correction amount is calculated for each cylinder in order to equalize rotational fluctuations between cylinders, and the fuel injection amount to be injected is corrected and controlled based on the correction amount. Has an excellent effect that misfire can be suppressed due to the increase correction.

In particular, claims 2, 3, 4, 6, 8, 9, 1
According to the first aspect of the invention, the above-described effects are more reliably achieved. In addition, according to the fifth and seventh aspects of the present invention, it is possible to further achieve both the effect of suppressing misfire and stabilizing the idle speed.

According to the tenth aspect of the present invention,
Exhaust emissions are prevented from deteriorating.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing a fuel injection control device for a multi-cylinder engine according to a first embodiment.

FIG. 2 is an enlarged sectional view showing a cylinder portion of the engine.

FIG. 3 is a flowchart showing a “correction amount calculation routine” executed by the ECU.

FIG. 4 is a flowchart illustrating a part of a “correction amount calculation routine” according to the second embodiment;

FIG. 5 is a flowchart illustrating a part of a “correction amount calculation routine” according to a third embodiment;

FIG. 6 is a flowchart illustrating a “correction amount calculation routine” according to a fourth embodiment;

FIG. 7 is a flowchart illustrating a “correction amount calculation routine” according to a fifth embodiment;

FIG. 8 is a flowchart illustrating a part of a “correction amount calculation routine” according to a sixth embodiment;

FIG. 9 is a flowchart illustrating a part of a “correction amount calculation routine” according to another embodiment;

[Explanation of symbols]

Reference numeral 1 denotes an engine as an internal combustion engine, 11 denotes a fuel injection valve,
25: throttle sensor, 26A: accelerator sensor, 2
6B: Fully closed switch, 27: Top dead center sensor, 28: Crank angle sensor, 29: Swirl control valve sensor, 30: Electronic control unit (ECU), 53: EGR valve, 61: Intake pressure sensor, 62: Water temperature sensor , 63 ... Vehicle speed sensor.

Claims (11)

[Claims] 1. A rotating state detecting means for detecting a rotating state of an internal combustion engine for each cylinder during an idle operation of a multi-cylinder internal combustion engine having a fuel injection valve for each cylinder, and a rotation detected by the rotating state detecting means. Injection correction amount calculating means for calculating a fuel injection correction amount for each cylinder, based on the state, in order to equalize rotational fluctuations between the cylinders, based on the calculation result of the injection correction amount calculation means, In a fuel injection control device for a multi-cylinder internal combustion engine, comprising: a correction control unit that corrects and controls an injected fuel injection amount; an operation state detection unit that detects an operation state of the internal combustion engine; and a detection of the operation state detection unit. The fuel injection correction amount calculated by the injection correction amount calculation means is changed according to the result, the fuel injection correction amount upper limit value is changed, the fuel injection amount increase correction limiting means for limiting the fuel injection amount increase correction means is provided. Fuel injection control apparatus of a multi-cylinder internal combustion engine that. 2. The fuel injection control device for a multi-cylinder internal combustion engine according to claim 1, wherein the increase correction restricting unit decreases the upper limit value when the load on the internal combustion engine is low. Fuel injection control device for a multi-cylinder internal combustion engine. 3. A rotation state detecting means for detecting a rotation state of the internal combustion engine for each cylinder during an idle operation of a multi-cylinder internal combustion engine having a fuel injection valve for each cylinder, and a rotation detected by the rotation state detection means. Injection correction amount calculating means for calculating a fuel injection correction amount for each cylinder, based on the state, in order to equalize rotational fluctuations between the cylinders, based on the calculation result of the injection correction amount calculation means, A fuel injection control device for a multi-cylinder internal combustion engine, comprising: a correction control unit that corrects and controls a fuel injection amount to be injected; a misfire detection unit that detects a misfire of the internal combustion engine; and a misfire is detected by the misfire detection unit. When the fuel injection amount is calculated, the fuel injection correction amount calculated by the injection correction amount calculation means is reduced by an upper limit value, and the fuel injection amount is corrected by an increase correction limit means. The fuel injection control apparatus for internal combustion engine. 4. The fuel injection control device for a multi-cylinder internal combustion engine according to claim 3, wherein the misfire detection means detects misfire for each cylinder, and the increase correction restriction means detects misfire. A fuel injection control device for a multi-cylinder internal combustion engine, wherein the upper limit value is reduced only for a closed cylinder. 5. The fuel injection control device for a multi-cylinder internal combustion engine according to claim 3, wherein the increase correction restricting means decreases the upper limit stepwise each time a misfire is detected. A fuel injection control device for a multi-cylinder internal combustion engine, characterized in that: 6. A rotation state detection means for detecting a rotation state of the internal combustion engine for each cylinder during an idle operation of a multi-cylinder internal combustion engine having a fuel injection valve for each cylinder, and a rotation detected by the rotation state detection means. Injection correction amount calculating means for calculating a fuel injection correction amount for each cylinder, based on the state, in order to equalize rotational fluctuations between the cylinders, based on the calculation result of the injection correction amount calculation means, A fuel injection control device for a multi-cylinder internal combustion engine, comprising: a correction control unit that corrects and controls a fuel injection amount to be injected; a misfire detection unit that detects a misfire of the internal combustion engine; and a misfire is detected by the misfire detection unit. The fuel injection correction amount calculated by the injection correction amount calculation means is reduced, the increase correction of the fuel injection amount is restricted, and the fuel injection correction amount is updated thereafter. The fuel injection control apparatus for a multi-cylinder internal combustion engine, characterized in that a and increase correction limit stop means for stopping. 7. The fuel injection control device for a multi-cylinder internal combustion engine according to claim 6, wherein the misfire detection means detects misfire for each cylinder, and the increase correction restriction stop means detects misfire. A fuel injection control device for a multi-cylinder internal combustion engine, wherein the fuel injection correction amount is reduced only for a selected cylinder. 8. A rotation state detecting means for detecting a rotation state of the internal combustion engine for each cylinder during idle operation of a multi-cylinder internal combustion engine having a fuel injection valve for each cylinder, and a rotation detected by the rotation state detection means. Injection correction amount calculating means for calculating a fuel injection correction amount for each cylinder, based on the state, in order to equalize rotational fluctuations between the cylinders, based on the calculation result of the injection correction amount calculation means, A fuel injection control device for a multi-cylinder internal combustion engine, comprising: a correction control unit that corrects and controls a fuel injection amount to be injected; a misfire detection unit that detects a misfire of the internal combustion engine; and a misfire is detected by the misfire detection unit. A correction control prohibiting unit that prohibits a correction control of the fuel injection amount based on a calculation result of the injection correction amount calculating unit after that. Fuel injection control device. 9. A rotation state detection means for detecting a rotation state of the internal combustion engine for each cylinder during an idle operation of a multi-cylinder internal combustion engine having a fuel injection valve for each cylinder, and a rotation detected by the rotation state detection means. Injection correction amount calculating means for calculating a fuel injection correction amount for each cylinder, based on the state, in order to equalize rotational fluctuations between the cylinders, based on the calculation result of the injection correction amount calculation means, A fuel injection control device for a multi-cylinder internal combustion engine, comprising: a correction control unit configured to correct and control an injected fuel injection amount. The fuel injection valve according to the fuel injection correction amount calculated by the injection correction amount calculation unit. A fuel injection control device for a multi-cylinder internal combustion engine, comprising: a misfire suppression control unit that controls an actuator different from the first embodiment to suppress misfire. 10. The fuel injection control device for a multi-cylinder internal combustion engine according to claim 9, wherein said misfire suppression control means controls a plurality of said actuators. Control device. 11. The fuel injection control device for a multi-cylinder internal combustion engine according to claim 9, wherein the actuator includes an exhaust gas recirculation control valve that adjusts an exhaust gas recirculation amount, and the misfire suppression control is performed. A fuel injection control device for a multi-cylinder internal combustion engine, wherein the means controls at least the exhaust gas recirculation control valve to reduce the amount of exhaust gas recirculation.