JPS60198347A - Air/fuel ratio controller for internal-combustion engine - Google Patents

Abstract

PURPOSE:To improve the control accuracy of an air/fuel ratio controller for lean combustion engine, by operating the air/fuel ratio on the basis of the insulation breakdown voltage of ignition means and the inner pressure of cylinder then performing feedback control of fuel supply on the basis of said air/fuel ratio. CONSTITUTION:Under engine operation, the combustion chamber pressure pig ignition and the peak level VB of ignition voltage vS variable with time are obtained respectively through cylinder inner pressure detecting means 20 and peak voltage decision means 21. While the instantaneous discharge resistance rS (=vS/ iS; where iS is the ignition current) is operated through discharge resistance operating means 22 then the average resistance RS is obtained from rS while the discharge time DS is decided in discharge time decision means 23 through variation of ignition current iS. Then actual air/fuel ratio A/F is operated 34 from pig and VB to operate 39 the correction factor (a) with correspondence to the comparison results between the absolute value of the difference DELTAA/F between said operated 34 value and the referential level and the referential level thus to correct the basic injection TP through correction operating means 40 with correspondence to said correction factor (a).

Description

Detailed Description of the Invention (Technical Field) The present invention relates to an air-fuel ratio control device for an internal combustion engine, and particularly to an air-fuel ratio control device for a lean-burn engine that performs combustion with a mixture having a lean stoichiometric air-fuel ratio.

(Technical background) With the tightening of exhaust gas regulations in automobile internal combustion engines, a three-way catalyst is installed in the exhaust system, which reduces the amount of HC and CO in the exhaust. t-
The exhaust gas is purified by oxidizing and reducing NOx.

Such a device is shown in FIG. A three-way catalyst reduces NOx (7) and HC when the air-fuel mixture is near the stoichiometric air-fuel ratio.

Together with the oxidation function of CO, it can be maximized.

Therefore, an oxygen sensor 3 that changes stepwise around the stoichiometric air-fuel ratio is attached to the exhaust pipe 2 upstream of the three-way catalyst 4, and based on the signal from this oxygen sensor 3, the control unit 5 controls the air-fuel ratio at around the stoichiometric air-fuel ratio. In order to always have energy,
The fuel supply amount t from the fuel injection valve l is feedback-controlled.

However, in recent years, there has been a demand for both cleaning exhaust gas and reducing engine fuel efficiency from the perspective of resource conservation, and in order to achieve these two goals at the same time, it is necessary to operate the engine in an air-fuel mixture range with a lean theoretical air-fuel ratio of 9. However, this type of device is advantageous, and such a device has been proposed (for example, in Japanese Patent Laid-Open No. 58-1
40449).

Therefore, when trying to generate feedback control sound by applying the three oxygen sensors mentioned above to a lean burn engine, the detection accuracy of the oxygen sensor 3 is only high near the stoichiometric air-fuel ratio, so when the air-fuel ratio is far away from the stoichiometric air-fuel ratio, It is not suitable for control at high speeds, and stable feedback control becomes difficult.

Also, since the 1ζ air-fuel ratio is set in the intake system and detected in the exhaust system, it is unavoidable that there will be a response delay in detection, and in actual control, this response delay should be taken into account. There must be.

Therefore, especially during acceleration, the response delay increases and fluctuations from the set air-fuel ratio tend to occur, resulting in deterioration of fuel efficiency and exhaust emissions.

(Object of the invention) The present invention directly detects a parameter representing the combustion state in the combustion chamber, which is closely related to the air-fuel ratio, and
An object of the present invention is to provide an air-fuel ratio control device that performs air-fuel ratio feedback control and has high control accuracy and high responsiveness even in a lean burn engine.

Furthermore, in addition to the first invention, the second invention provides a fuel ratio control device that generates an appropriate flow of gas in the cylinder, thereby simultaneously achieving improved fuel efficiency and clearing the regulation value for emissions of NOx, etc. purpose.

(Disclosure of the Invention) FIG. 2 is an overall configuration diagram for clearly showing the constituent sounds of the present invention. The 4° fuel supply control means includes the basic injection amount calculation means 25. It is composed of fuel supply means 16.

That is, the basic injection amount calculation means 25 calculates the basic injection amount so as to obtain an air-fuel ratio of R leaner than the stoichiometric air-fuel ratio based on the engine speed and engine load, and based on the calculation result, The drive means 26 drives the fuel supply means 16;
Supply fuel to the engine.

Note that the engine speed is detected by a rotation speed detection flat membrane 11 (for example, a rotation sensor such as a crank angle sensor), and the engine load is detected by a load detection means 12 (for example, a suction negative pressure sensor, an air flow meter).

The fuel supply means 16 is composed of a fuel injection device in a fuel injection type engine, and an electronic control device in a carburetor type engine.

In this case, in the fuel injection device, the injection noculus width k'Nt
IJ control, electronically controlled vaporizer, Airbu IJ -)"
Control the duty ratio of a solenoid valve that opens and closes at k high and j side wave numbers.

Here, considering the fuel WVe that is lower than the lean mixture where the stoichiometric air-fuel ratio sound is far off, combustion in this lean mixture range is inherently prone to misfires, and this step is aimed at stabilizing lean combustion. For this purpose, a long discharge plasma ignition means (long discharge plasma ignition means, gas flow control means) is provided.

In other words, the long-discharge plasma ignition means ensures reliable ignition, shortens the subsequent initial combustion time, and suppresses combustion fluctuations. It is something that

Therefore, specifically regarding the combustion customization of lean burn engines,
This will be explained first based on FIG. 11.

The influence of gas flow on engine stability is large in the lean air-fuel ratio region, and compared to when the gas flow is weak (marked by the broken line), if the gas flow is moderately strengthened by 111TUk, the effect on the lean air-fuel ratio side will be much greater. The stability limit expands (towards the right in the figure).

However, if the current is increased to an excessively high level (denoted by the dashed-dotted line), the flame propagation during combustion will not be extinguished, but on the contrary, combustion fluctuations will occur and the stability limit sound image comb-r L Mau.

In this 1st step, an appropriate gas flow strength is required.

In order to maintain NOx emissions below the regulation level without a catalyst, the air-fuel ratio must be leaner than AIFI.

As a result, 1'v' becomes 'x (!: ■'z)'wv
It becomes a lean air-fuel ratio range where it is possible to clear the regulation 1st shift without installing a three-way catalyst, etc., and to achieve the same improvement in fuel efficiency, and the air-fuel ratio falls within this range. If you control it properly, it will become better.

Therefore, in actual control, the median value of W is assumed to be the set air-fuel ratio A/Fok, and the basic injection amount calculation means 25 adjusts the basic injection amount to the set air-fuel ratio A/F'o according to the operating conditions. The air-fuel ratio correction means (1), which will be described later,
The minute width ξA/F (ε class ゛〈W
/2) to keep the actual air-fuel ratio within
It's hack control.

In this way, since the lean air-fuel ratio range to be subjected to feedback control has been determined, it is next necessary to detect the actual air-fuel ratio.

Therefore, in the present invention, among the seven meters in the combustion chamber that directly affect NOx emissions and fuel efficiency, parameters that are closely related to the air-fuel ratio are selected. Adopted and air fuel ratio? We will detect it.

First, if we look at the relationship between the air-fuel ratio and the discharge characteristics, we will see the relationship shown in Figure 6.

In the same figure, the dielectric breakdown voltage VB (see Figure 5) varies with the change in the air-fuel ratio A/F (1).
Although it does not change much near th, it changes sharply in a lean air-fuel ratio range where A/Fthk is far off, so in this range, it is possible to accurately set LvA/F' for Vnk detection.

In addition, since the cat strongly depends on the combustion chamber pressure (pressure between the spark plug electrodes) Pig at the time of ignition according to Paschen's law (see Figure 7), A/F is given as a function of VB and pjg. , VB and 91g are determined, A/F is determined.

On the other hand, as mentioned above, the strength of the gas flow determines the lean side limit value of W (Fig. 11), so it is necessary to maintain an appropriate Uk by setting the gas flow strength and gas flow velocity). be.

Figure 8 shows the relationship between U and discharge characteristics.

Figure 9.

In the same figure, as U increases, the discharge resistance ratio increases,
On the other hand, the discharge time Ds decreases (see Figure 5 1.
R8U 1 is the averaged instantaneous discharge resistance rsk that changes over time during ignition, 1 Therefore, U is R
It is given as a function of s and Ds, and if gs and Ds are determined, U is determined.

As described above, in the present invention, the four parameters vn l pig + R8 + D are used for feedback control of the air-fuel ratio.
S? We will adopt them.

Therefore, returning to FIG. 2, the constituent parts of 9.1 m will be explained.

In order to measure the four parameters, cylinder pressure detection means 20.
Peak voltage determining means 21. Discharge resistance calculation means 22. A discharge time determining means 23 is provided.

The ignition voltage detection means 181 and the ignition current detection means 19 detect the ignition voltage v8 supplied from the long discharge plasma ignition means.
Two ignition currents i5 (see FIG. 5 for both) are of course detected respectively.

Starting with the cylinder pressure detection means 20, the cylinder pressure detection means 20 first detects Pig k.

The peak voltage determining means 21 determines 8f, which is the peak value of v5 that changes with time.

The discharge resistance calculation means 22 is v5 and i5,! 7rs (
= vs/is) and calculate the average discharge resistance 1tS4 from r5.

The discharge time determining means 23 determines the change in i5↓diDsk.

Next, based on the pig and vB, the actual air-fuel ratio M(2
To explain the fuel supply correction means that performs feedback correction on A/Fo, the first stage of this fuel supply correction means includes reference value setting means 35, 37, air-fuel ratio change correction means 36. Comparison means 38. Correction coefficient calculation means 39° correction calculation means 40
That is, the air-fuel ratio calculating means 34 calculates the actual air-fuel ratio A/F' based on the PIG detected by the cylinder pressure detecting means 20 and the VB detected by the peak voltage determining means 21. do.

The air-fuel ratio change calculation means 36 calculates the difference ΔA/F (=A/Fo A/F) k between this A/F and the reference value A/FO set in advance by the reference value setting means 35. do.

The comparison means 38 compares I△A/F l and the reference value setting means 3
7, the preset reference value εA/Fk is compared.

In this case, 1△A/F l represents the actual deviation of the set air-fuel ratio A/F'op, etc., and εA/F represents the allowable range of deviation, so I△A/F l falls within εA/F. But if you are, no problem! If ΔA/F l is outside of εA/F', it must be kept within 1ΔA/Flig, AlF.

Therefore, in the case of 1△A/Fl>εA/F, the correction coefficient calculation means 39 calculates the correction coefficient α(−△
A/F) Perform all calculations.

The correction calculation means 40 corrects the basic injection lid Tpk using this αt feedback correction coefficient.

For example, if the air-fuel ratio exceeds εA/F' and deviates to the lean air-fuel ratio side, the Tpk increase is corrected and ? If the air-fuel ratio exceeds A/F'k and deviates from the stoichiometric air-fuel ratio side, T is corrected to reduce the air-fuel ratio.

In this way, the fuel supply amount correction means performs air-fuel ratio t feedback control.

Next, gas flow correction means for maintaining the gas flow strength at an appropriate level will be explained. In this case, the control by the gas flow correction means is similar to the control by the fuel supply correction means described above in the sense that the gas flow strength is maintained at a set value based on the actual detected value.

That is, the gas flow correction means 29. Reference value setting means 28, 30. Comparison means 31. Drive pulse width calculation means 32. A driving means 33 is constructed.

Starting from the gas flow calculation means 27, the gas flow calculation means 27 calculates the actual U' based on gs calculated by the discharge resistance calculation means 22 and Ds determined by the discharge time determination means 23.

The gas flow change amount calculation means 29 uses this U and the reference value U preset by the reference value setting means 28.

The difference ΔU (=Uo−U)'? calculate. Comparison means 31
Now, 1ΔU1 is compared with a reference value εU preset by the reference value setting means 30.

In this case, 1△U1 represents the actual deviation from the set flow rate Uo, and 6U represents the allowable deviation range, so if I△U1 is within ευ, there is no problem, but 1△U1 is ε
If it is outside υ, it needs to be within 1Δliευ.

Therefore, in the case of 1△Ul>εU, the drive pulse width calculation stage 32 fully calculates the drive pulse width T (=△U) corresponding to △U, and based on this T, the drive means 33 controls the gas flow means 1
7 actuator wwAA works.

For example, the gas flow means 17 is provided in a main intake boat located downstream of the intake throttle valve, and in a sub-intake boat with a small cross-sectional area that branches from the main intake boat and joins again near the intake valve. A second throttle valve separate from the intake throttle valve is installed in the main intake boat, and when the second throttle valve is closed,
There are some that increase the amount of gas flowing to the sub-intake port, increasing the flow rate of the gas flow.

In this case, if I△U1 exceeds εUk and the flow velocity is high, the opening of the second throttle valve is increased to reduce the amount of gas flowing into the sub-intake port, thereby reducing the flow velocity and noise. In addition, when 1ΔU1 exceeds εvk and the flow velocity becomes slow, the opening degree of the second throttle valve is conversely decreased to increase the flow velocity.

In this way, the gas flow correction means maintains the strength of the waste flow at the set value.

Therefore, the set air-fuel ratio is determined by the parameter obtained in the combustion chamber! Since direct feedback control is required, the acceleration response becomes even better, and
The S engine can also realize a lean-burn engine that improves fuel efficiency and satisfies exhaust emission regulations within engine stability limits.

(Example) FIG. 3 is a schematic diagram of an embodiment of the present invention.

First, to explain the long discharge plasma ignition device, the long discharge plasma ignition device has a primary winding 52 and a secondary winding 53.
7] Ignition coil 51 with /4' transistor 54. Distributor 55. plasma ignition plug 5
6a to 56d, and a DC-DC3 inverter 57.

That is, when the ignition coil primary current is cut off based on the ignition signal S1 from the means for detecting the ignition timing in synchronization with the engine rotation, a high voltage is induced on the secondary side of the ignition coil 51. It is supplied to plasma ignition plugs 56a to 56d.

In the plasma ignition plugs 56a to 56d, a high temperature, high energy thermal glaze flow is generated in the discharge gear lug to ignite the fuel.

Further, the DC-DC converter 57 is installed by taking advantage of the fact that once the spark discharge of the five spark plugs has occurred, the discharge action continues at a voltage lower than the dielectric breakdown voltage vB. The converter 57 supplies a high voltage sufficient to sustain the discharge action, superimposed on the high voltage generated by the negative current cutoff, thereby extending the discharge duration (
(See ignition current 1B9 ignition voltage v8 in FIG. 5).

Therefore, the long-discharge plasma ignition device aims to ensure reliable ignition in lean combustion, shorten the subsequent initial combustion time, and suppress combustion fluctuations.

In addition, VBAT is battery 1kC pressure y1, V2U
This is the reference voltage created from VBAT.

Next, the peak voltage discriminator 60 is connected to the resistor 61. Buffer amplifier 62.66, inverting amplifier 63. Peak hold (b)
Road 64. It is composed of a sample and hold circuit 65 and the like, and holds the ignition voltage vs flowing to the secondary side of the ignition coil 51 at a peak value VB (breakdown voltage)', and outputs a peak voltage vB'v.

Note that the actual dielectric breakdown voltage vB is a high voltage on the order of kV, so the voltage is dropped to the order of ■ through 61 high resistances, and vB' = c - vB (C: constant,
There is a relationship (C<<1) (see Figure 5).

The discharge time discriminator 70 includes a converter tough 12 inversion circuit 7
3. Consisting of 72.74 monomultipipe lakes,
1 Determine the discharge time Dsk at ignition (see Figure 5) 5
, That is, the period from the rise of the mono multi-pipe break 72 to 9 o'clock when the mono multi-pipe break 74 rises is Ds.

The discharge resistance calculation circuit 80 includes buffer amplifiers 81 and 82.
, A/D converters 83, 84 . It is composed of a division circuit 85.

That is, the discharge voltage ys' (=CHVs), the discharge current isl: are converted into digital values via the A/D converters 83 and 84'lr, and from the converted values,
In the division (b) path 85, the discharge resistance rs' (= VB'/
is) 'r:, is calculated, and the calculation result t is output to the control unit 90 as a digital value.

On the other hand, the cylinder pressure sensor 42 is formed, for example, in the shape of a spark plug washer, and by attaching this sensor 42i to the combustion chamber wall together with the spark plug, the combustion chamber pressure PIG at the time of ignition can be taken out as a signal. can.

The suction negative pressure sensor 43 detects the negative pressure p in the intake pipe corresponding to the engine load, and the rotation sensor 44 detects the engine (b) rotation speed N.
Detect sound.

Since the detection values of these sensors 42 to 44 are analog values,
The signals are converted into F-digital values by A/D converters 45 to 47 and then output to the controller 90.

In addition to the suction negative pressure sensor 43, an air flow meter that detects the amount of intake air may be used. (In addition to the quadruple sensor 44, a crank angle sensor may also be used.) If you use ° signals,
Since it is already a digital value, no A/D converter is required.

In this way, the peak voltage discriminator 60. Discharge time discriminator 70
．． V obtained from the discharge resistance calculation circuit so, m internal pressure sensor 42, suction negative pressure sensor 439 and rotation sensor 44, respectively.
B' r DS r rS' r plg p p+
Based on H, the control unit 90 controls the fuel supply device 94 and the gas flow device 100? ]:Control.

In this case, the fuel supply device 94 includes, for example, a fuel injection device or an electronically controlled carburetor, and in the case of a fuel injection device, the valve opening period (corresponding to the fuel injection amount) of the fuel injection valve is adjusted. By doing so, the air-fuel ratio is controlled.

Further, the gas flow @ device 100 will be further explained based on FIG. 4.

In the figure, a sub-intake port with a small cross-sectional area branches from the main intake boat 105 to the intake blood path 101 downstream of the intake throttle valve 102 and rejoins the main intake boat 105 near the intake valve 103.
A second throttle valve 107 separate from the intake throttle valve 102 is installed in the main intake boat 105.

Note that the sub-intake boat 106 causes a gas flow flowing into the combustion chamber 104 when the second throttle valve 107 is closed to create a swirl flow. It opens toward the combustion chamber 104 so as to occur.

At this point, the flow velocity U of the gas flow generated in the combustion chamber 104 changes depending on the opening degree of the second throttle valve 107. For example, if Uk is to be decreased, the second throttle valve 107
7, the valve opening sound is increased and the gas flow is adjusted to the main intake boat 105.
All you have to do is make it flow as much as possible.

The link rod 108 extends the operation of the second throttle valve 107τ.
? Actuator (servo motor) 10 connected via
At 9, the servo motor 109 is constituted by, for example, a step motor that follows the rotation angle in synchronization with the input Norse frequency.

Then, the control unit 90e controls the U sound through the valve opening degree of the second throttle valve 107 by adjusting the frequency of this individual coupler.

Returning to FIG. 3, the control unit 90 will be explained. This control unit 90 is a microcomputer that performs digital control 7, and mainly includes human output signal processing circuits (Ilo) 91. Central processing unit (CI) U) 92
, a storage device ([01Vl) 93 sword\, etc., and the detected number 1g is inputted to Ilo 91 as a digital signal.

Note that the output signal of the peak voltage discriminator 60 is also converted into a digital signal.

Next, the operation of the above configuration will be explained based on the flowchart of FIG. 10.

The basic injection amount Tp of fuel that provides an air-fuel ratio tray that is even leaner than the stoichiometric air-fuel ratio is determined in advance by R with respect to the suction negative pressure p and the engine speed N.
The detected p and N'? are stored in the OM93. ! - 9Tp for fc three-dimensional table lookup with lattice axis
(Ps P2).

In this case, if the fuel supply device 94 performs fuel supply amount sound control using a fuel injection valve of a fuel injection device, this Tp
' may be set to give the valve opening period of the fuel injection valve, and when a signal with this Tpk noggle width is output to the fuel injection valve, fuel is supplied for this period and the stoichiometric air-fuel ratio J
, 9, a lean mixture will also be formed.

In reality, this Tpk is further output as the Te w drive/gust width which has been corrected for fuel temperature, water temperature, etc. (P
le Plt).

Note that Te is given by Te=T, (1+α+γ), where α represents a feedback correction coefficient (described later), and γ represents correction coefficients based on fuel temperature, water temperature, etc.

Next, feedback control of the air-fuel ratio will be explained. In this control calculation, a comparison is made between the actual detected air-fuel ratio and a preset 1ζ air-fuel ratio.

Specifically, by table lookup given ↓9 for p and N, the reference value A/Fo of the lean air-fuel ratio is determined,
The allowable width εA/
F (see Figure 11) and readout (P+).

Ps).

On the other hand, the actual air-fuel ratio A/F k must be calculated to be compared with this reference value A/l;

Therefore, A/F is the function f of pig and vB in the above-mentioned process.
Given by Katana 1 et al., A/F = f (plg,
VB), A/F i calculation (or table lookup) may be used, but in this control, P+g
For r Vn, the average value p+g r vn at a specific time
k adopted 1°, that is, pig = (1/m)Σ[
)ig + VB = (17m)Σvn (however, V
B'=C-VB)'e calculate (PR, P)).

Note that m is a positive integer, p, mx (control'@arithmetic period is set as a specific time.

Therefore, A/F is given as the function pf between pig and vB, and A/F is [)ig (!: VB7 lattice axis f
7+3? In the original table lookup, J is raped.
Plo).

Next, in order to see whether the deviation between A/F and A/Fo is within εA/F or not, the air-fuel ratio deviation ΔA/F (= A/FO - h /F) absolute value 1△A/F ltεA/F (P12~P□
4).

If IΔA/F I is within εA/F', there is no need for correction (Pl4-P2□), but 1ΔA/F' l
If it exceeds εA, /F, in order to return the air-fuel ratio to within εA/F, the correction coefficient α is calculated as α = △A/F (Pl4-Pls). For example, if A/F is εA/F ' If it deviates to the lean side (rightward in Figure 11) by 1, then
α (=△A/F) ) becomes 0, Tp is corrected to increase, and the air-fuel ratio becomes the stoichiometric air-fuel ratio A/Fthil again! Move to ll.

Similarly, when A/F deviates to the A/Fth side, α becomes 0, Tp is corrected to decrease, and the air-fuel ratio moves to the lean side. .

In this way, the air-fuel ratio is corrected and controlled within the allowable range εA/F.

On the other hand, regarding the gas flow velocity U, it was mentioned earlier that U is given as a function of DS and R8.
For R8, we also adopted the average value bS + R8k for a specific time, and performed a three-dimensional table lookup with US and Rsχ lattice axes.9 U7. (Read, this read *,
Value Uk A reference value U of the flow rate of gas flow stored in the ROM 93 in advance. Compare with (Pl, P3~P5 + ps
+P9upu ) 0 In this case, the average discharge resistance R8 per ignition is Rs
= (1/n) Chu (Vs/is) (7r-dashi,...-〇....

Note that the allowable width εU of Uo7)h and others is also read out at the same time.

Therefore, if 1△U1 exceeds εU and is off, for example, if the flow velocity is off the cut and small, then △U > 0 and 7 ),
The drive signal generated by the T-engine 9 is output to the step motor (
P18~Pzo),.

In this case, when T (=ΔU)>0, the opening degree of the second throttle valve 107 is increased, and the sub-intake port 10
6 increases, the flow velocity in the combustion chamber 104? Enlarge.

When T is 0, the flow velocity is reduced, contrary to the above-described operation, and the flow velocity eventually falls within the control range.

Note that when IΔU1 falls within 6U, the step motor 109 is not operated (Pla P22).

As a result, a moderate gas flow rate is maintained and the engine stability limits are expanded and maintained.

Then, in the lean air-fuel ratio region formed between this expanded 1ζ stability limit and the position where the NOx emission regulation value is cleared even without the installation of a catalyst, the air-fuel ratio is precisely feedback-controlled ( (See Figure 11).

(Effects of the Invention) As described above, according to the present invention, parameters closely related to the air-fuel ratio obtained in the combustion chamber are directly adopted as parameters for performing correction control. The performance has been significantly improved, and it shows its true potential, especially when accelerating.

In addition, the second
The lean air-fuel ratio correction control of the invention provides the best fuel efficiency.

This makes it possible to meet NOx emissions regulations and maintain engine stability at the same time, making it possible to realize a high-quality lean-burn engine.

Furthermore, by detecting the parameters in the combustion chamber for each cylinder, it is possible to control the air-fuel ratio sound by adding the parameters between the cylinders (However, in this case, the fuel supply system, gas flow system By adopting all systems that can operate independently for each cylinder, it becomes possible to perform air-fuel ratio feedback control for each cylinder, making it possible to realize even higher-quality lean-burn engines.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram of a conventional device. FIG. 2 is an overall configuration diagram clearly showing the structure of the present invention. FIG. 3 is a schematic configuration diagram of an embodiment of the present invention, and FIG. 4 is a longitudinal sectional view of a gas flow device. Fig. 5 is an explanatory diagram showing the spark discharge characteristics and the output characteristics of the peak voltage discriminator and ignition time discriminator. Fig. 6 is a diagram showing the relationship between breakdown voltage and air-fuel ratio, and Fig. 7 is a diagram showing the ignition pressure. FIG. 8 and FIG. 9 are diagrams showing the discharge time and discharge resistance, respectively, with respect to the flow rate of gas flow. FIG. 10 is a diagram showing the relationship between 11 is an explanatory diagram showing engine stability, NOx emissions, and fuel efficiency in a lean air-fuel ratio region. 11... Rotation speed detection means, 12... Load detection means,
16...Fuel supply means, 17...Gas movable means, 1
8... Ignition voltage detection means, 19... Ignition current detection means, 21... Peak voltage discrimination means, 22... Discharge resistance calculation means, 23... Discharge time discrimination means, 25...
Basic injection amount calculation means, 26... Drive means, 27...
Gas flow calculation means, 28.30... reference value setting means,
29... Gas flow change amount calculation means, 31... Comparison means, 32... Drive pulse width calculation means, 33... Drive means, 34... Air-fuel ratio calculation means, 35.37... Reference value setting means, 36... Air-fuel ratio change amount calculation means, 38
... Comparison means, 39 ... Correction coefficient calculation means, 40.
... Correction calculation means, 42 ... Cylinder pressure sensor, 43 ...
- Suction negative pressure sensor, 44... Rotation sensor, 51...
Ignition coil, 54...Power transistor, 56a-5
6d... Plasma ignition plug, 57... DC-DC converter, 60... Peak voltage discriminator, 70... Discharge time discriminator, 80... Discharge resistance calculation circuit, 90...
・Control unit, 94...Fuel supply device, 1
00... Gas flow device, 101... Intake passage, 10
2... Intake throttle valve, 103... Intake valve, 104...
Combustion chamber, 105...Main intake port, 106...Sub-intake port 1, 107...Second throttle valve, 109...Servo motor. Patent applicant Nissan Motor Co., Ltd. Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 Figure 9

Claims (1)

[Claims] 1. An ignition means attached to the combustion chamber and a fuel supply control means for controlling the amount of fuel supplied so that a predetermined lean air-fuel ratio can be obtained based on the detected value of the operating state of the engine. In the internal combustion engine, means for detecting the entire dielectric breakdown voltage due to the ignition means, in-cylinder pressure detecting means for detecting the in-cylinder pressure, and air-fuel ratio calculating means for calculating the entire air-fuel ratio of combustion gas based on the outputs of these two means; An air-fuel ratio control device for an internal combustion engine, comprising a fuel supply amount correction means for feedback controlling the fuel supply amount based on the detected air-fuel ratio. 2. The air-fuel ratio control device for an internal combustion engine according to claim 1, wherein the ignition means is a plasma long discharge ignition means. 3. In an internal combustion engine comprising an ignition means attached to a combustion chamber and a fuel supply control means for controlling the fuel supply amount so that a predetermined air-fuel ratio is obtained based on a detected value of the operating state of the engine, the ignition means means for detecting dielectric breakdown voltage caused by;
cylinder pressure detection means for detecting cylinder pressure noise; air-fuel ratio calculation means for calculating the air-fuel ratio of combustion gas based on the outputs of these means; and fuel for feedback control of the fuel supply amount based on the detected air-fuel ratio. a supply amount correction means, a gas flow means for variably generating in-cylinder gas flow, a means for detecting the discharge time and discharge resistance sound of the ignition means, and a gas flow strength calculating means based on these detection results. An air-fuel ratio control device for an internal combustion engine, comprising: a flow calculator; and a gas flow correction means for feedback-controlling the gas flow means so that the calculated value becomes a set value.