JPH02286844A - Air-fuel ratio control method for internal combustion engine with supercharger - Google Patents

Abstract

PURPOSE:To reduce the rate of fuel consumption and smoothen torque variation likely to be generated when acceleration/deceleration is made into part of the supercharger range, by controlling the air-fuel ration to the lean side when this supercharger- equipped internal cumbustion engine lies in part of the supercharge range. CONSTITUTION:Control device 5 of an internal combustion engine 1 equipped with a supercharger 7 judges that the engine is operating in the supercharge range if the absolute pressure in suction pipe sensed by an absolute pressure sensor 9 exceeds a certain specified value, and judges that it is out of the supercharge range if the value is below the specified, and then sets the air fuel ratio to the theoretical value of air fuel ratio in off-supercharge range and on the rich side in supercharge range. The air-fuel ratio is, however, set on the lean side in part of the supercharge range, i.e. where the absolute pressure in the suction pipe is over specified value and below No.2 specified value, and where the engine revolving speed sensed by an engine rotation sensor 11 is below specified value. Thus the rate of fuel consumption can be reduced, and torque variation when acceleration is made from part of the supercharge range into other supercharge range, or when it takes place oppositely, can be smoothened, that is assisted by simultaneous changing of the ignition timing.

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to an air-fuel ratio control method for a supercharged internal combustion engine, and is particularly aimed at improving fuel efficiency, etc. in the supercharging range of a supercharged internal combustion engine. This invention relates to an air-fuel ratio control method.

(Prior art and its problems) Conventionally, as is known from, for example, Japanese Patent Application Laid-Open No. 59-85439, in an internal combustion engine equipped with a supercharger, when the engine is in the supercharging range, the air-fuel ratio is controlled to the rich side. Increase output and improve acceleration 1. I try to do that. However, when cruising at high speeds in the supercharging range, the vehicle usually travels for a long time, so controlling the air-fuel ratio to the rich side as described above causes a problem of high fuel consumption and poor fuel efficiency.

Furthermore, especially in internal combustion engines with a turbocharger, there is a delay in the rotation JJT due to the inertia of the supercharger, so there is a time delay before supercharging pressure is generated, and the required acceleration cannot be achieved instantly. There were also problems.

(Object of the Invention) The present invention has been made to solve the problems of the prior art described above, and aims to improve fuel efficiency in the high-speed cruising region within the supercharging region, and to improve fuel efficiency from the non-supercharging region to the supercharging region. The purpose is to improve the acceleration performance when accelerating.

(Steps for Solving the Problem) In order to achieve the above object, the first invention provides a supercharging system that controls the air-fuel ratio of the air-fuel mixture supplied to the engine (J) according to the operating state of the internal combustion engine. Machine 4=I In the air-fuel ratio control method for an internal combustion engine, when the engine is in a part of the supercharging region, 1
); It is characterized by controlling the air-fuel ratio (1) to the lean side.

The second invention provides a supercharger i.
In the air-fuel ratio control method for an internal combustion engine, when the engine is in a part of the supercharging region, 1); 1: the air-fuel ratio is controlled to the lean side; 0; j: from a part of the supercharging region to the supercharging region; This is characterized by controlling the air-fuel ratio to a predetermined rich value and at the same time reducing the engine output when the engine shifts to a high performance section.

The third invention provides 1% supercharging (
=1 In an air-fuel ratio control method for an internal combustion engine, the air-fuel ratio is controlled to the lean side when the engine is in a part of the supercharging region, while the air-fuel ratio is controlled to the lean side when the engine is in a part of the supercharging region. When the temperature shifts to 11, the air-fuel ratio is controlled to a predetermined rich value, and at the same time the engine output is reduced.
It is characterized in that when the engine shifts from another part of the supercharging region described in 1j to a part of the supercharging region, the air-fuel ratio is controlled to a predetermined lean value and at the same time the engine output is returned to the original value. be.

(Example) Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a block diagram showing the overall configuration of a fuel supply control device for a supercharged internal combustion engine to which the air-fuel ratio control method of the present invention is applied. The symbol 1 indicates, for example, a four-cylinder internal combustion engine. An intake pipe 2 is connected to the engine 1, and a throttle valve 3 is provided in the middle of the intake pipe 2. A throttle valve opening (□T11) sensor 4 is connected to the throttle valve 3, which detects the valve opening θ and outputs an electrical signal.The detected valve opening OTl+ is sent to the electronic control unit. l- (hereinafter referred to as r IE CU J) 5.

A fuel injection valve 6 is provided between the engine l and the throttle valve 3. The fuel injection valve 1 is provided for each cylinder of the engine 1, is connected to a fuel pump (not shown), and controls the valve opening time for injecting fuel by a drive signal supplied from the ECU 3. .

An exhaust pipe 13 is connected to the engine 1, and a turbine 7Fl of a supercharger 7 is disposed in the exhaust pipe. The compressor 7b provided at

- On the other hand, an absolute pressure (+)B^) sensor 9 is connected to the intake pipe 2 of the throttle valve 3 via a pipe 8 to detect the absolute pressure 1)I]^ in the intake pipe 2. The detection signal Y) is sent to 1ζCU5.

An engine filled with coolant! An engine water Ml (TW) sensor 10, which is made of a thermistor and detects the cooling water temperature 1'w, is provided on the cylinder peripheral wall of the engine.
The detection signal is sent to the ECU 3.

Engine rotation speed (Ne) sensor 11 and air Pj determination (C
YL) A sensor 12 is attached around the camshaft or crankshaft (not shown) of the engine l, and the sensor 11 outputs l pulse every 180'' rotation of the crankshaft.
outputs an l pulse at a predetermined angular position of the crank as a signal for identifying the cylinder, and these pulse signals are sent to the ECU 3.

A three-way catalyst 14 is installed in the exhaust pipe 13 of the engine l,
It purifies IIC, Go, and NOx components in exhaust gas. An oxygen (02) sensor 15 as an exhaust gas concentration sensor is attached to the exhaust pipe 13 on the first stream side of the three-way catalyst 14, and the sensor I5 detects the oxygen concentration in the exhaust gas and supplies a detection signal to the ECU 5. are doing.

Further, an engine operating parameter sensor 16 for measuring atmospheric pressure, intake pressure, etc. is connected to the ECU 3, and the sensor 16 supplies a detection signal to the ECU 5.
17 is installed in the main body of the engine L, and the ignition device consists of an ignition circuit, a distributor, a spark plug, etc.
It is connected to the CU 5, and ignition timing and the like are controlled by control signals from the ECU 3.

1': The CU 5 inputs the various signals described in Section 11 and calculates the fuel injection time 1'OUT of the fuel injection valve 6 using the following equation.

1'out=i' i XKO2XKI+ to 2・-・(
1) Here, Ti is the reference injection time of the fuel injection valve 6, the engine rotation speed Ne detected from the Ne sensor It, and the absolute pressure signal from the absolute pressure sensor 9! It is calculated according to 'R^. KO2 is an air-fuel ratio correction coefficient that is set according to the oxygen concentration indicated by the detection signal of the 02 sensor 15 during air-fuel ratio feedback control, and is set to a predetermined value ( For example, it is set to the average value KREF of the correction coefficient KO2 values set during feedback control.

K+ and 2 are the various sensors mentioned above, namely the throttle valve opening sensor 4, the intake pipe absolute pressure sensor 9, the engine water temperature sensor TO, the Ne sensor II, the cylinder discrimination sensor 12, and other parameter sensors! Other correction coefficients and correction variables are calculated according to the engine parameter signals from 6, and are used to optimize starting characteristics, exhaust gas characteristics, fuel efficiency characteristics, engine acceleration characteristics, etc., depending on the engine operating condition. Calculations are made based on predetermined calculation formulas, maps, etc. so that

ECU3 calculates the fuel injection time 'I' calculated by formula (1).
A drive control signal based on o u T is supplied to the fuel injection valve to control its amount valve time.

In addition, the ignition timing is calculated by the ECU 3 according to the operating state of the engine, and a control signal corresponding to the calculated ignition timing is sent to the ECU 3.
It is supplied from the CU3 to the ignition device 7.

FIG. 2 shows an air-fuel ratio map used for air-fuel ratio control according to the present invention. In this map, a region R+ where the intake pipe absolute pressure Pa is below a predetermined value P81 is a non-supercharging region, and Pa1
The above region R2 is the supercharging region.

Furthermore, a part of the supercharging region, that is, a region R* where the engine speed Ne is below the predetermined engine speed Ne1, the intake pipe absolute pressure Ps is the predetermined value 1's+'2 or more, and the predetermined value 1'R2 or more F (Ne≦Net, I'R1≦P n(P n2
) is considered to be the lean area according to the present invention. This region corresponds to high-speed cruising conditions, such as 180 to 200 km/l+. The air-fuel ratio is set to a first predetermined value Δ1 (for example, the stoichiometric air-fuel ratio 1/1) when the engine is in the non-supercharging region 1/1.
1.7), and when it is in supercharging region 1 and 2, it is set to a second predetermined value Δ2 (for example, 12.5) on the rich side. On the other hand, when the engine is in the region 1 to 3, which is a part of the supercharging region, the air-fuel ratio changes to a third predetermined value on the lean side (for example, 16.
0).

Figure 3 shows the air-fuel ratio A/17, fuel efficiency 13S I"C, and torque '1 when a general internal combustion engine is in the high load range.
゛ is 1 to 1 showing the relationship with the exhaust temperature 'l'l1ix. As the air-fuel ratio/[7 becomes lean from the rich side, the fuel consumption n5Fc decreases and becomes the lowest near the lean third predetermined value A3 (16,0). On the other hand, the exhaust temperature 'rεX increases by 1 as the air-fuel ratio becomes leaner,
.

The maximum temperature occurs near the stoichiometric air-fuel ratio of 14.7, but as the air-fuel ratio becomes leaner, the exhaust temperature increases to '1゛ε.
X gradually decreases until it reaches the third predetermined value of 16.0, which is almost the same as the exhaust gas temperature when the air-fuel ratio A2 (12,5) is on the rich side. Furthermore, the torque 1' decreases as the air-fuel ratio becomes leaner.

Therefore, in the high load range, the air-fuel ratio Δ/F is set to a lean value,
For example, by setting the value to 16.0, it is possible to reduce fuel consumption while suppressing a 1-increase in exhaust gas temperature. Incidentally, as mentioned above, the torque 'I' decreases due to the lean air-fuel ratio, but this does not pose a problem since high torque is not required so much during high-speed cruising.

FIG. 4 shows the fuel efficiency improvement effect of the air-fuel ratio control according to the present invention, and shows the engine speed Ne (Ne(Net)
The relationship between intake pipe absolute pressure Ps, torque '1゛, and fuel consumption +3 S lW C is expressed as air-fuel ratio Δ2, A
When the air-fuel ratio Δ/F expressed in each case of 3 is set to a rich air-fuel ratio Δ2, the absolute pressure in the intake pipe becomes a predetermined 1lI.
IPI]z (for example +100w++I1g), the fuel efficiency obtained when the torque is rO is b eA
z, whereas the air-fuel ratio A/1? When set to the lean air-fuel ratio Δ3, the fuel consumption required to obtain the same torque '1゛o is 1 river^1 (<IJ (uA2). - As an example, the fuel consumption be^2.L )O^1 is 227g/p each
s, h, 18f1g/ps, b, so 38g/
It saves as much as ps and it in fuel consumption. In addition, since lean combustion lowers the combustion temperature by 4.4 degrees and therefore the exhaust temperature, adverse effects on the three-way catalyst can also be avoided.

In Figure 5, is the engine in the non-supercharged region 1? This explains the stepped phenomenon of torque that occurs when acceleration from + to rich supercharging region R2 through lean supercharging region Ra or deceleration in the opposite direction, and when the air-fuel ratio is AI, A2. The relationship between the intake pipe absolute pressure 1) and the torque "I" at A3 is shown. The transition from the non-supercharging region R+ to the lean supercharging region 1b is carried out smoothly by gradually leanening the air-fuel ratio from Δ+ (14,7) to Δ* (16,0). do not have. On the other hand, when transitioning from the lean supercharging region R3 (0 point) to the rich supercharging region +<2 (Iζ point), the air-fuel ratio changes from Δy (1 (i, 0) to the stoichiometric air-fuel ratio A+ (1/ 1
．． 7) and gradually change it to A2 (12,5), the stoichiometric air-fuel ratio will be reached! It passes through the vicinity, but
When the air-fuel ratio is near A1, the combustion temperature becomes high, and therefore the exhaust temperature becomes high, which is not preferable. Therefore, this transition is performed by rapidly changing the air-fuel ratio from A3 to A2, but in this case, a stepped phenomenon of l·lux occurs. On the contrary, 1ζ
Exactly the same can be said for the transition from point to zero (rich-lean).

FIG. 6 is for explaining the method of eliminating the torque stepping phenomenon described in item 1 according to the present invention.
I, A2. It shows the relationship between ignition timing Oig and torque T in case of A3. According to the method of the present invention, when transitioning from the lean supercharging region R3 (point 0) to the rich supercharging region R2 (point E), the air-fuel ratio is changed from A3 (16,0) to A2.
(12,5) and at the same time directly enrich the ignition timing.
Ignition timing Oigs or ignition timing Oi at point igti-C
This is to retard the angle to gz.

The ignition timing (7Ig2 is the same torque (1) point as the torque (0 point) obtained when the air-fuel ratio is A3) is delayed with respect to the ignition timing Oigm so that it can be obtained when the air-fuel ratio becomes A2. is set to the value specified. As a result, supercharging area R3
A sudden torque change 1L caused by enriching the air-fuel ratio when shifting from to R2 is suppressed. The same thing can be said for the transition from point E to point 0 (rich-lean).

7 to 1I show programs for executing the air-fuel ratio control method of the present invention. These programs are
l) Executed in synchronization with each C signal. First, the program shown in FIG. 7 determines whether the engine is in the acceleration/deceleration control mode or the normal control mode. In step 71, it is determined whether the absolute 1f[1ΔO group 1 of the throttle valve opening change claw ΔO group 1 is larger than a predetermined acceleration determination value α. If the answer is Yes, that is, if A0 ``Moe〉α is established and it is determined that the engine operating state is in a transient state, the acceleration/deceleration mode shown in FIG. 8 is executed (step 72 ).The answer to step 71 is negative (
In the case of No), if it is determined that the operating state of the engine is in a steady state, that is, in the cruising or slow acceleration/deceleration range ['1], the normal control mode shown in Fig. 1) is executed (step 73).

In the acceleration/deceleration control mode shown in FIG. 8, first, in steps 81-83, it is determined whether the engine is in the enriched supercharging region 1)2. That is, in step 81, it is determined whether or not the engine speed Ne is less than or equal to the predetermined value Ne+1):1.If the answer is affirmative (Yes), the absolute pressure PB in the intake pipe is set to the predetermined value Ne+ in step 82. Determine whether the answer is 11 (Yes).
In this case, in step 8:3, it is determined whether the absolute pressure Ps in the intake pipe is less than or equal to the predetermined value pH2-1. 11; If the answer to step 83 of step 1 is affirmative (Yes), the determination is I 1
il II or i'! i (step 84)
. If this answer is 1°r constant, that is, when the engine shifts (accelerates) from the lean supercharging region 1b to the rich supercharging region 1 to 2 for the first time, the stepped compensation ilE subroutine shown in FIG. 1 (step 85).

On the other hand, if the answer to step 83 is negative (No), that is, if it is determined that the engine is in the lean supercharging region 1 or 3, the determination is made once [1] is determined (step 8G).
. If this answer is affirmative (Yes), that is, when the engine shifts (decelerates) from the rich supercharging region R2 to the monotonizing supercharging region 1 to 3, the Step 1・1
Then execute hli 1l-9 bluegin 2 (step 87).

Also, the answer to step 81 or 82 in FIG. 8 is fi constant (No
), that is, the engine speed No is equal to the predetermined value Ne+
or the intake pipe absolute pressure 1'n is the predetermined value P+++
In the following case, the normal control mode of step 121 is executed. Also, in step 84, the answer to 8 is ?'F constant (
If NO), the normal control command is executed.

In the normal control mode shown in FIG. 1, first, in step 91, it is determined whether the intake pipe absolute pressure 1''II is equal to or less than a predetermined value 1''I;
If the answer is affirmative (YoS), it is determined in step 92 whether the intake pipe absolute pressure Pn is equal to the predetermined value 111' (P n 2 or more), and if the answer is 1" (Yes), In step 93, the engine speed Ne or the predetermined value Ne is determined.
Determine whether + or less, and the answer is affirmative (Yes)
In this case, that is, when it is determined that the engine is in the lean supercharging region 1-3, the air-fuel ratio is controlled to Δ3 (16,0) (step 94).

On the other hand, if the answer to step 91 is negative (NO), that is, if it is determined that the engine is in the non-supercharging region R+, the air-fuel ratio is controlled to A1 (theoretical air-fuel ratio 14,7) (step 9
5). Further, if the answer to step 92 is negative (No), that is, if it is determined that the engine is in the rich supercharging region R2, the air-fuel ratio is controlled to A2 (12, 5) (step 9
6).

In the stepped correction subroutine shown in FIG. 10, first, in step 101, the ignition timing Oig is retarded to Oig2, and at the same time, the air-fuel ratio is changed from A3 to A2 rich (step 102). By retarding the ignition timing, torque is maintained even when the air-fuel ratio is enriched! 7 (point C in Figure 6 → 1
), sudden torque changes are avoided. In addition, the air-fuel ratio is immediately enriched from A3 to A2, so the exhaust temperature is reduced.
Noboru is also avoided. Next, in step 103, it is determined whether the ignition timing 01g is equal to Oig+. This time, the loop is a loop that retards Oig to Oig2, so
The answer is No, and in step 104 the control 6111 variable n is set to a predetermined value 11αn x (for example, 3).
Determine whether or not. If the answer is negative (No), +1 is added to the control 1 variable U in step 105. Steps 104 and 105 are repeatedly executed until the answer to step 105 becomes affirmative (Y(38). When the answer to step 104 becomes +' (Yes) (72
,=7ZX), reset n to O in step 106 h l
After that, during ignition, FLIO1g is advanced to the optimum ignition timing (Qig+) at which the maximum torque is obtained at the air-fuel ratio A2 (step +07).

(Point 1)→Point 1ζ in FIG. 11) In this embodiment, in the cylinder immediately after acceleration from the supercharging region 121 to the supercharging region 122, after the ignition timing is retarded, the next 'r
I) When a pulse occurs, the retarded ignition timing is advanced to the optimum ignition timing.

Next, after executing step 106, return to step +03 to determine whether the ignition timing is equal to Oig'/J<Oig+, and if the answer is affirmative (Yes), 1 normal control I/roll mode (step 108) to move to.

In the step A/1 correction mode 2 in FIG.
11, the ignition timing Qig is retarded to a predetermined ignition timing Oig2, and the output is controlled to the low torque side (6th
Figure 13 points → 1) points). Then, in step +12,
It is determined whether the ignition timing O1g is equal to 01y,+. This time, the loop is a loop in which Oig is delayed to Oigz, so the answer is negative (No), and step 1 in Figure 10
Steps 113 and 114 are executed exactly as in 04.105. When the answer to step 113 is affirmative (Yos) (7Z=7Zx), after resetting 7Z to 0 (step +15), the ignition timing 01g is advanced,
At the same time, the air-fuel ratio is leanened from A2 to A3 (steps I16 and I17). As described above, in this embodiment, after retarding the ignition timing at the corresponding air 1:1i immediately after deceleration from 2 to the supercharging area IL+ in the supercharging area L, the ignition timing is retarded at the air [11
When the next '1''l) C pulse occurs, the retarded ignition timing is advanced to the optimum ignition timing Oig+, and at the same time,
The air-fuel ratio is made lean. By advancing the ignition timing, torque is maintained even if the air-fuel ratio is made lean (1 in Figure 6).
point → point C), and since the air-fuel ratio is immediately leanened from A2 to A3, an increase in exhaust temperature is also avoided. Next, after executing steps 116 and 117, the process returns to step +12 to determine whether the ignition timing O1g71J (equal to Olgl). If the answer is affirmative (Yes), the routine shifts to the normal control mode (step 118).

As described in -1- above, according to the present invention, when the engine is in the lean supercharging region 1<a, the air-fuel ratio is controlled to the lean side to improve fuel efficiency, etc. When moving from 1) to rich supercharging region 1≧2, or from rich supercharging region 1)2 to lean supercharging region 1<3, 11; Correction subroutine l
By adjusting the ignition timing O1g using 11. This allows for a smooth transition.

Furthermore, according to a modification of the present invention, 1): It is possible to improve the acceleration performance of the supercharger 1; 1 engine by utilizing the torque stage (step 1 phenomenon) shown in FIG. Generally speaking, when accelerating an engine with a supercharger f=J, there is a delay in the rotor J/ due to the inertia of the supercharger, so there is a time delay in supplying the amount of intake air necessary to increase the torque, which reduces acceleration. On the other hand, according to the air-fuel ratio control of the present invention, the air-fuel ratio is enriched during acceleration from the lean supercharging region 1 to the rich supercharging region R2, so the supercharging S'Z first when the rotation speed of the machine increases
Since the engine torque increases by 4, there is almost no time delay in increasing the torque, so the acceleration response can be increased to 11.

Fig. 12 shows 1) 1, which explains the direction of the A-speed responsiveness due to the air-fuel ratio control according to the present invention. In other words, in FIG. 6, as mentioned above, when transitioning from the lean supercharging region R3 (0 point) to the rich supercharging region R2 (1ζ point), the air-fuel ratio is changed to Δ・鵞(16, 0) to A2
(12,5), and at the same time retards the ignition timing Oig from the ignition timing Oig+ at the 0 point to the ignition timing 01g2. ) so that the same torque (point D) can be obtained when the air-fuel ratio becomes A2.
It is set to a value that lags behind +. On the other hand, the 12th
In the figure, the torque (0 point) is higher than the torque (0 point).
The ignition timing O1y, 2' to be retarded is set so that point 1]' is obtained when the air-fuel ratio reaches A2.

1) 1 point is selected to be an appropriate value between 1) point and 13 points depending on the desired acceleration response. The transition from l)' point to 1ζ point is the maximum l at air-fuel ratio △2, as in the example described above.
・This is done by advancing the ignition timing to the optimum ignition timing Oig+ that provides the desired torque. In this way, when accelerating from the supercharging region Rt (0 point), the air-fuel ratio is changed from A3 (16,0) to A2 (12,5
) and at the same time retard the ignition timing Oig from the ignition timing Oig+ at point 0 to the ignition timing Oig2',
By advancing the ignition timing 0'+y to rI degrees Oig+, the torque drop due to the retardation of the ignition timing is reduced, and the torque change required for acceleration (point C → point 1' → point I3) can be obtained. . Since torque changes due to air-fuel ratio control and changes in ignition timing occur instantaneously,
]: Due to the increase in Sakishima°L, the engine output is 111L.
/, good acceleration response is obtained. .

(Effects of the Invention) As described below-1-IIY, according to the supercharger A.1 air-fuel ratio control method for an internal combustion engine of the present invention, the air-fuel mixture supplied to the engine is controlled according to the operating state of the internal combustion engine. Supercharger 1 for controlling an air-fuel ratio of 4° Air-fuel ratio control of an internal combustion engine (one method is characterized in that the air-fuel ratio is controlled to a lean side when the engine is in a supercharging region) Therefore, fuel consumption is reduced.7 In addition, the torque fluctuation when accelerating from the - part of the supercharging region to the supercharging region, or when decelerating to a part of the supercharging region, is calculated by adjusting the air-fuel ratio. The engine output can be changed by changing the ignition timing at the same time as ridge or lean control (1'J), so it can be made smoother. Also, it can accelerate from the - part of the supercharging region to the supercharging region of the function. At this time, the air-fuel ratio control by increasing the fuel t' causes an instantaneous increase of 1~l.
There is no visible time delay, and the acceleration response is improved by -1'.

FFTI LIT DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing an embodiment of a fuel supply control device for an internal combustion engine to which the air-fuel ratio control method according to the present invention is applied, and FIG. 2 shows an air-fuel ratio map according to the present invention. Figure shown, 3rd
1ri1 is the fuel efficiency and torque due to the air-fuel ratio control according to the present invention,
Fig. 4 is a diagram showing the characteristics of exhaust temperature;
The figure shows the stage of torque during air-fuel ratio control according to the present invention.
FIG. 6 is a diagram showing the relationship between ignition timing and torque, and FIG. FIG. 7 is a flowchart v-1 of a program for determining and selecting a control mode, which is part of the air-fuel ratio control program according to the present invention.
・, Figure 8 is the flowchart of acceleration/deceleration control mode (I program flowchart 1), Figure 8 is the flowchart of the normal control mode control program, Figures 10 and 11
The figures show a flowchart I for torque stage f.1 and hliton motor 1.2, respectively, and Fig. 12 explains a modification example for achieving an acceleration response of +1 in the direction of -1- by the air-fuel ratio control of the present invention. It is a diagram.

1...Internal combustion engine, 2...Intake pipe, 5...Electric control unit h (1': (,LJ),
(i.Fuel↑11 injection valve, 7.Supercharger, 9.Intake pipe shoe, 1 sensor, 11.Engine speed sensor.

Sacrifice 20

Claims (1)

[Claims] 1. In an air-fuel ratio control method for a supercharged internal combustion engine, which controls the air-fuel ratio of a mixture supplied to the engine according to the operating state of the internal combustion engine, the engine is part of a supercharging region. An air-fuel ratio control method for a supercharged internal combustion engine, characterized in that the air-fuel ratio is controlled to a lean side when the air-fuel ratio is on the lean side. 2. In the air-fuel ratio control method for a supercharged internal combustion engine, which controls the air-fuel ratio of the air-fuel mixture supplied to the engine according to the operating state of the internal combustion engine, when the engine is in a part of the supercharging region, the air-fuel ratio while controlling the air-fuel ratio to a predetermined rich value when the engine moves from one part of the supercharging region to another part of the supercharging region, and at the same time reducing the engine output. A method for controlling the air-fuel ratio of an internal combustion engine with a supercharger. 3. In the air-fuel ratio control method for a supercharged internal combustion engine, which controls the air-fuel ratio of the air-fuel mixture supplied to the engine according to the operating state of the internal combustion engine, when the engine is in a part of the supercharging region, the air-fuel ratio while controlling the air-fuel ratio to a predetermined rich value when the engine moves from one part of the supercharging region to another part of the supercharging region, simultaneously reducing the engine output and A supercharger characterized in that when the engine moves from another part of the supercharging region to a part of the supercharging region, the air-fuel ratio is controlled to a predetermined lean value and at the same time the engine output is returned to the original state. Air-fuel ratio control method for internal combustion engines. 4. The air-fuel ratio control method for a supercharged internal combustion engine according to claim 2 or 3, wherein the output of the engine is changed by changing the ignition timing of the engine.