JPS63183231A - Control device for air-fuel ratio of internal combustion engine - Google Patents

Abstract

PURPOSE:To perform accurate air-fuel ratio control even in the case a fresh intake blow-through rate makes complicated changes by calculating a fresh intake capture factor from a multi-dimensional map corresponding to an operating condition of an internal combustion engine and adding a compensation to a basic fuel injection rate determined by load and rpm. CONSTITUTION:A 2-cycle internal combustion engine 1 or the like having a great blow-through rate of fresh intake is provided with a means 2 for supplying a required rate of fuel and a means 5 for calculating a fuel supply rate determined by the operating condition of the internal com. bustion engine 1. A means 4 is also provided for storing compensation data for compensating the blow- through of the fresh intake corresponding to multiple combinations of plural operating conditions of the internal combustion engine 1. A means 5 is further provided for calculating the compensation factor suitable for the measured operating conditions of the engine 1 and for correcting the fuel supply rate calculated with the means 3. A means 6 is further provided for forming a fuel supply signal of a corrected amount to be outputted to the means 2.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a fuel supply amount control device suitable for a two-stroke internal combustion engine. Further, the present invention can be applied to a four-cycle internal combustion engine, such as a four-valve engine, which has a long pulp overlap period and has a large amount of fresh air blown through.

[Conventional technology]

In a two-stroke internal combustion engine, the period during which the intake port and exhaust port are in communication for scavenging is extremely long. If fuel is supplied to the cylinder in the form of a mixture using a carburetor as usual, it is directly discharged into the exhaust system through a blow-through. It is often done. Therefore, a system has been proposed in which a fuel injector is installed and fuel is injected only during a predetermined period in the intake cycle of the engine. However, even if such a fuel injection system is adopted, the problem of intake air blow-by itself cannot be eliminated. In other words, in a two-stroke internal combustion engine, the fresh air taken in is blown directly into the exhaust pipe without participating in total heat combustion within the cylinder bore, and the amount of fresh air that is actually involved in combustion is smaller than the amount of air that passes through the engine intake system. The amount of air in the cylinder bore decreases, and the proportion of air that blows through changes depending on engine operating conditions such as load and rotation speed. On the other hand, the amount of fuel supplied to the engine is calculated from the amount of air passing through the intake system based on the set air-fuel ratio. Therefore, in a two-stroke internal combustion engine, the amount of injected fuel no longer corresponds to the amount of air actually involved in combustion within the cylinder bore, making it impossible to maintain the air-fuel ratio at the set value.

Therefore, JP-A No. 53-27731 proposes a method in which a correction is made according to the blow-through ratio to the basic injection amount determined by the engine load and rotation speed, and the corrected amount of fuel is injected. are doing. Here, the correction amount is changed according to an algebraic function such as an I-number function depending on the intake air amount and the engine speed. In other words, the amount of correction is
The change in intake air amount and engine speed is approximated to an exponential function, and the basic injection amount is corrected to obtain the final amount of fuel injected.

[Problem that the invention seeks to solve]

The conventional technology is based on the idea that the change in the blow-through ratio depending on the operating conditions is assumed to change exponentially, and correction is performed. However, changes in the blow-through ratio depending on operating conditions become extremely complicated due to the influence of exhaust gas blowdown, for example, and it is extremely difficult to compensate for the blow-through ratio using a simple algebraic function. Therefore, it is not possible to accurately know the amount of air that actually exists in the cylinder bore and participates in combustion, and as a result, it is not possible to accurately control the air-fuel ratio to the set value. Therefore, there are problems such as overheating of the catalyst and deterioration of fuel consumption rate.

SUMMARY OF THE INVENTION An object of the present invention is to accurately control the air-fuel ratio to a set value even if the blow-through ratio changes in a complex manner depending on engine operating conditions.

[Means for solving problems]

According to this invention, in FIG. 1, in an internal combustion engine with a large amount of fresh air blowing through, such as a two-stroke internal combustion engine, the air-fuel ratio control device supplies a desired amount of fuel to the internal combustion engine l. Means 2, fuel supply amount calculation means 3 which calculates the fuel supply amount determined by the operating conditions of the internal combustion engine such as load and rotation speed, A storage means 4 for storing correction factor data for compensating for blow-through, and a fuel supply amount calculation means for interpolating the value of the correction factor that matches the actually measured operating conditions of the internal combustion engine from the data stored in the storage means. 3, and means 6 for forming a fuel supply signal to the fuel supply means 2 so that the corrected amount of fuel is supplied to the engine. Ru.

[For production]

The fuel supply amount calculation means 3 calculates the fuel supply amount according to the load and the rotation speed, and the fuel supply amount correction means 5 calculates the fuel supply amount according to the multidimensional map of fuel supply amount correction factors stored in the storage means 4.
The fuel supply amount is corrected according to the fresh air blow-through amount, and the fuel supply signal forming means 6 forms a signal to the fuel supply means 2 so that the corrected fuel supply amount is obtained.

〔Example〕

FIG. 2 schematically shows the overall configuration of a six-cylinder two-stroke internal combustion engine having an intake valve and an exhaust valve to which the present invention is applied, and FIG. 3 shows one cylinder.

As will be explained later, this type of two-stroke internal combustion engine generates an exhaust swirl during the backflow of exhaust gas after blowdown, creating a stratification effect in which fresh air is concentrated near the spark plug at the top of the combustion chamber. This was devised to improve ignitability during operation. However, the present invention is not limited to this type of two-stroke internal combustion engine, but can also be applied to ordinary piston pulp type two-stroke internal combustion engines. Furthermore, even in a 4-stroke internal combustion engine, the idea of this invention can be applied to a 4-valve type engine where the valve overlap period is long and there is a lot of intake air blow-through, as shown in Figure 2.3. , 10 is the main body of the internal combustion engine, which includes a cylinder block 12, a cylinder bore 14, a crankshaft 15, a piston 16, and a combustion chamber 1.
7, a cylinder head 18, and a spark plug 19.

The cylinder head 18 has two intake boats 20a and 20b.
.

It has two exhaust boats 22a, 22b, each intake boat has an intake valve 24a, 24b for opening and closing the exhaust port.
It is a so-called 4-pulp type equipped with exhaust valves 26a and 26b. The intake valve and the exhaust valve are driven to open and close by dedicated cams 27 and 28, respectively. 30.31 is a valve spring. The exhaust bows 22a and 22b are selected to have a shape such that when the exhaust gas flows back into the cylinder bore due to its negative pressure after blowdown, a swirl movement of the exhaust gas is obtained in the cylinder bore about its vertical axis. Ru.

In FIG. 2, numeral 32 indicates a surge tank, which is connected to intake pipes 33 whose number matches the number of cylinders.

The intake pipe 33 has an internal partition wall 33-1, and two intake passages 34a and 34b are formed, each of which is connected to the intake boat 20a.
, 20b. The second intake passage 34b has a larger effective dimension than the first intake passage 34a, and is provided with an intake control valve 36.

The intake control valve 36 of each cylinder is connected to an actuator 37 by link means 36'. The actuator 37 is, for example, a diaphragm mechanism operating under negative pressure, and is switched between negative pressure and atmospheric pressure by a switching valve (not shown), and the intake control valve 36 is at a position where it opens the intake passage 34b.
The closed position can be selectively taken. As will be described later, the intake control valve 36 is closed when the load is light and opened when the load is high. Fuel injectors 38a, 38b are arranged in intake passages 34a, 34b. 40a.

40b is a reed valve, which is installed as necessary to control backflow.

An intercooler 42, a mechanical supercharger 44, a throttle valve 46, an air flow meter 48, and an air cleaner 50 are arranged in this order in the intake system upstream of the surge tank 32. The mechanical supercharger 44 is configured by, for example, a roots pump or a vane pump, and has a pulley 52 on its drive shaft 44-1 and is connected to a pulley 56 on the crankshaft 15 by a belt 54. A bypass control valve 45 is installed in a bypass passage 44' that bypasses the supercharger 44 and controls the pressure between the supercharger 44 and the throttle valve 46. The ink cooler 42 is configured as an air-cooled type in this embodiment, and has an inlet container 42-1 and an outlet container 42-1.
-2, a heat exchange tube 42-3 communicating therebetween, and fins 42-4 attached on the heat exchange tube 42-3.

In this embodiment, two exhaust manifolds 54 are separately installed for cylinder groups #1 to #3 and cylinder groups #4 to #6, respectively.

This grouping is such that ignition alternates between these two groups. That is, in this example, the firing order is #1. #6. #2. #4゜#3. Assume that the order is #5. By grouping the cylinders with alternating ignition, it is possible to prevent the exhaust pressure of one cylinder from being affected by the exhaust pressure of other cylinders during the scavenging stroke, as will be described later. Cylinder groups #l~#3, #4~
The exhaust manifolds 54 of the #6 cylinder group are each connected to a dedicated catalytic converter 56 (which may also be used as a muffler or a dedicated muffler may be installed separately).

A distributor 58 is, as is well known, connected to the spark plug 19 of each cylinder and controlled by an igniter and an ignition coil (not shown) so that ignition is performed at a desired crank angle.

The control circuit 60 controls the operation of the injectors 38a and 38b so as to obtain a desired air-fuel ratio according to the present invention, and is configured as a microcomputer system. The control circuit 60 includes a microprocessing unit (MPtJ) 60-1, a memory 60-2, input ports 0-3, output ports 0-4, and a bus 60-5 connecting these. Input port 0
-3 is connected to each sensor and receives an operating condition signal. The F-flow meter 48 may be of a volumetric flow rate type, and measures the flow IQ of intake air passing through the intake pipe. The present invention can also be applied to a fuel injection system in which a pressure sensor for detecting intake pipe pressure is installed instead of an air flow meter. In this case, a semiconductor-type intake pipe pressure sensor 61 is installed downstream of the throttle valve 46 and upstream of the supercharger 44, and generates a signal corresponding to the intake pipe pressure PM. In this embodiment where a bypass passage 44' is installed, the pressure sensor 61 is installed in the bypass passage 44' so that the pressure is not affected by the bypass air flow rate.
It is preferable to install it upstream of the connection point. If the supercharging system does not include a bypass, it is also possible to install a pressure sensor downstream of the supercharger. A crank angle sensor 62,64 is installed on the distributor 58. The first crank angle sensor 62 is disposed facing the magnet piece 58-2 fixed on the distributor shaft 58-1, and is arranged so as to face the magnet piece 58-2 fixed on the distributor shaft 58-1.
It generates a pulse signal (equivalent to a cycle) and serves as a reference signal. On the other hand, the second crank angle sensor 64 is installed facing the magnet piece 58-3 on the distributor shaft 58-1, and generates a pulse signal every 30 degrees of the crank angle, for example, so that the engine speed can be determined. , which is the start signal for the fuel injection routine. A water temperature sensor 68 is installed in the engine body lO and generates a signal according to the temperature T HW of the cooling water in the water jacket 10-1.

The MPU 60-1 executes arithmetic processing according to the program and data stored in the memory 60-2, and controls the intake control valve actuator 37 and injectors 38a and 38b.
The drive signal forming process is executed. Output port 0-
4 is connected to an actuator 37 and fuel injectors 38a and 38b of each cylinder, and a drive signal is applied thereto.

FIG. 4 shows an intake valve 24a in one cylinder determined by the profile and orientation of cams 27 and 28.

24b and the operation timings of the exhaust valves 26a and 26b. First, the intake valves 24a, 24b and the exhaust valves 26a, 26b begin to open at 80'' before bottom dead center (BDC) and end closing at 40° after bottom dead center (BDC).On the other hand, the intake valves 24a, 24b Point (B D C) 60° in front
It begins to open at 60" after bottom dead center (B D C) and closes at 60" after bottom dead center (B D C). In addition, ■ indicates the fuel injection period. Figure 5 shows the operating period of the exhaust valve in each cylinder relative to the crank angle. This is a timing diagram shown in Figure 1. Since it is a two-cycle engine,
At 360 DEG CA - the cycle is completed, and according to the firing order the exhaust valve is opened for the period EX shown in FIG. 3 every 60 DEG of crank angle. One group that collects every other cylinder in the firing order (#1 to #3 or #4 to #6)
Specifically, the exhaust valves are opened every 1206 times, and in each group, the opening periods of the exhaust valves do not overlap between adjacent cylinders in the firing order. This prevents the exhaust pressure of one cylinder from affecting the exhaust pressure of the next cylinder in the group to be fired. In other words, the exhaust pressure pulsates due to the effect of blowdown, but when this pulsation is transmitted to other cylinders, the pressure changes in an unpredictable manner, resulting in a loss of predictability in the amount of fresh air blown through. This is prevented because the objective of the present invention, which is to accurately compensate the air-fuel ratio according to the amount of air blow-through, cannot be achieved. On the other hand, including the two groups, the exhaust valve opening period overlaps between cylinders with adjacent ignition orders, but
Since the exhaust manifolds 54 are separate between these cylinders, the exhaust pressure of one cylinder does not affect the exhaust pressure of other cylinders.

First, the combustion operation of a two-stroke internal combustion engine equipped with an intake valve and an exhaust valve to which the present invention is applied will be explained. When the engine is under light load, the intake control valve 36 is closed and intake air is introduced into the engine only through the first intake passage 34a. During the downward movement of the piston 16, the exhaust valves 26a and 26b first begin to open around 80 degrees before bottom dead center (BDC).

Therefore, the exhaust gas from the combustion chamber moves to arrow P in Figure 6 (a).
As shown in the figure, the exhaust boats 22a, :Hb are discharged, and a so-called blowdown occurs, but since this blowdown is weak, it ends immediately, and the exhaust boats 1-22a.

Since the cylinder to be ignited next belongs to a group other than another exhaust manifold 54, the pressure of the cylinder 22b is not affected by the exhaust pressure of that cylinder. When the piston 16 further descends, the inside of the cylinder bore 14 becomes a weak but negative pressure, and the pressure difference between the exhaust ports 22a and 22b causes exhaust gas to flow back toward the cylinder bore as shown by arrow Q (see Fig. 6). )), and exhaust port 26
a.

Because of the shape of 26b, a swirl of exhaust gas as shown by arrow R is formed in the cylinder bore. These days,
The intake valve 24a (also 24b) begins to open, but its lift is still small, the throttle valve 46 is throttled, the intake control valve 36 is closed, the intake passage 34b with a large effective dimension is closed, and the effective dimension small intake passage 34
As the piston 16 moves further down, the swirl of exhaust gas continues, while the intake valve 24a.

As the lift of 24b increases, fresh air is introduced into the cylinder bore as shown by arrow S, and at this time, the exhaust gas rides on the swirl and moves to the lower part of the cylinder bore 14, while the fresh air mixed with the injected fuel flows into the swirled exhaust gas. Stratification is achieved by gathering near the spark plug electrode above the gas section (FIG. 6(c)). This stratified state of the exhaust gas R and fresh air S is maintained even when the piston reaches the bottom dead center (BDC) (FIG. 6(d)). (E) Intake valve 24a
, 24b are closed to prevent fresh air from blowing back. The piston then moves upward, but this stratified state is maintained until compression is completed, making it easy to ignite the Niimi part near the spark plug.

In high engine load conditions, the intake control valve 36 is opened.

Therefore, the intake passage 34b, which has been closed until now, is opened. In FIG. 7, when the exhaust valves 26a and 26b open during the downward movement of the piston 16, the exhaust gas in the cylinder bore 14 is blown down by the exhaust boat 22a,
22b, but the blowdown is stronger and lasts longer than when the load is light (Figure 7 (a)).
A large amount of exhaust gas is discharged into the exhaust port. The intake valves 24a and 24b begin to open at the time shown in FIG. Since it is operating, fresh air is introduced as shown by arrow T. At this time, fresh air is introduced from both the intake boats 20a and 20b, and this fresh air flows from top to bottom along the cylinder bore wall as shown by arrow T, and the exhaust gas is transferred to the exhaust boat 22a as shown by arrow U. , 22b, so-called cross-scavenging air is realized. At the time point in FIG. 7(c), a negative pressure component appears in the pressure wave pulse due to strong blowdown, and the exhaust boats 22a and 22b temporarily become negative pressure, which further promotes the introduction of fresh air T into the cylinder bore. A part of the fresh air flows out to the exhaust boats 22a and 22b like V and is stored. This stored fresh air is transferred to the exhaust port 22a
.

When the pressure in 22b returns to positive pressure, it flows back into the cylinder bore as shown by arrow W, producing fresh air swirl X (FIG. 7 (d)). This causes turbulence and improves flame propagation after ignition. At the time of FIG. 7(E), the intake valve 24a
, 24b completes the closure and fresh air is prevented from blowing back.

Next, the operation of the control circuit 60 that operates the intake control valve 36 in the combustion operation described above will be explained with reference to the flowchart of FIG. This routine can be executed at regular intervals.

In step 100, it is determined whether the flag FTVIS=1. When FTVIS = O, step 102
Then, the intake air amount to revolution speed ratio Q/NE is set to a predetermined value (Q/NE).
NE).

In step 104, it is determined whether the rotation speed NI! is the predetermined value (NE). It is determined whether or not the value is larger than that. Intake air amount to rotation speed ratio Q/NE > Predetermined value (Q/NU
).

Or rotation speed NE>predetermined value (NE). Step 1
Proceed to 06 and actuator 3 from output port 0-4.
7, a signal for opening the intake control valve 36 is output.

At step 108, the flag PTVTS=1 is set. When FTVIS = 1, the process advances to step 110, and the intake air amount-to-rotation speed ratio Q/NE is determined to be equal to the predetermined value (Q/NE
)+, and in step 112, it is determined whether the rotational speed NE is smaller than a predetermined value (NE)r. Intake air amount to rotation speed ratio Q/NE <predetermined value (Q
/NE), and rotational speed NE<predetermined value (NE) I, the process proceeds to step 114, and a signal for causing the actuator 37 to close the intake control valve 36 is output from the output ports 0-4. In step 116, the flag FTVIS is
= set to 0.

Next, fuel injection control according to the present invention will be explained.

Similar to a normal fuel injection control device for a four-stroke engine, the principle of this invention is to measure the amount of intake air and obtain the desired air-fuel ratio each time the amount of fuel is injected according to the measured value. That is. However, similar problems occur in ordinary piston-valve two-stroke internal combustion engines, and because the exhaust valve and intake valve are held open at the same time for a long period of time, there are many problems of fresh air blowing through. and,
The proportion of fresh air that blows through changes depending on the load, rotation speed, and other operating conditions. Therefore, JP-A-53-27
As in No. 731, it is proposed to compensate for the blow-through by algebraic function approximation. However, in a two-stroke internal combustion engine equipped with an intake valve and an exhaust valve as in the present invention, the exhaust gas pressure pulsates due to blowdown, and the blow-through ratio changes in a complex manner accordingly, making it difficult to accurately approximate it by a simple exponential function approximation. No compensation can be provided. In addition, in the case where the blow-through ratio changes discontinuously depending on the opening and closing of the intake control valve 36 as in the present invention, it is extremely difficult to accurately compensate the air-fuel ratio according to the blow-through ratio using a simple algebraic function. Have difficulty. Therefore, in this invention, the memory 60-2
Data on fresh air capture coefficients corresponding to multiple operating conditions is stored inside the engine, and the fresh air capture coefficients are calculated by interpolation during actual operation, and the fuel injection amount is corrected based on this data. This allows the desired air-fuel ratio to be obtained even if the ratio changes depending on operating conditions.

FIG. 9 shows the fuel injection routine, and this routine is a crank angle interrupt routine that is executed every time the 30'CA signal from the second crank angle sensor 64 arrives. In step 130, it is determined whether or not it is fuel injection calculation timing. As shown in FIG. 3, fuel injection is performed within a predetermined angle range after the intake valves 24a, 24b begin to open, so this calculation is executed at a predetermined crank angle slightly prior to this. This timing is cleared by the 3600CA signal from the first crank angle sensor 62, and the second
This can be known from the value of the counter that is incremented based on the 30"CA multiplied signal from the crank angle sensor 64. If it is determined that it is the fuel injection calculation timing, step 1
Proceeding to step 32, the basic fuel injection amount 'rp is calculated by Tp=k (Q'/NE). Here, Q' is the intake air jlQ converted into mass, and is the value after correcting the measured value of the air flow meter 48 by the intake air temperature and the like. (PM can be used instead of Q'/NE in a system that determines the fuel injection amount based on intake pipe pressure PM.) Step 13
4, a map calculation of the fresh air capture coefficient rv* is executed.

Here, the fresh air capture coefficient fTll is the air flow meter 48
This is a correction factor for the amount of fuel injection related to the proportion of fresh air actually involved in combustion within the cylinder bore, which is calculated by subtracting the amount of fresh air that has flowed out into the exhaust system due to blow-through from the amount of intake air measured by . FIG. 1O conceptually shows how the fresh air capture coefficient fTll changes with respect to the intake air amount-to-rotation speed ratio and the rotation speed.

It can be seen that the intake air amount-to-rotation speed ratio and the rotation speed change in a complicated manner due to the influence of pressure pulsations in the exhaust pipe due to blowdown (the case where there is no influence from blowdown is shown by a broken line). It can also be seen that when the intake control valve 36 is switched between open and closed, the fresh air capture coefficient fTl changes discontinuously at the boundary (see the two-dot chain line). memory 60
-2 stores the data of the fresh air capture coefficient fTll for the combination of the intake air amount/rotation speed ratio and the rotation speed according to FIG. 1O. Then, an interpolation calculation is performed using the actually measured intake air amount-to-rotation speed ratio and the rotation speed, and a fresh air capture coefficient fTl that is suitable for the current operating conditions is calculated. In a system that determines the fuel injection amount based on the intake pipe pressure PM, a map of the fresh air capture coefficient fTll is constructed based on the combination of PM and rotational speed, and an interpolation calculation is performed based on the intake pipe pressure actually measured by the pressure sensor 61. . Furthermore, in the embodiment, the basic fuel injection is first calculated and then corrected by multiplying it by the fresh air capture coefficient rv*. The basic fuel injection amount may be calculated from the intake air amount.

In step 136, the fresh air capture coefficient f□ is calculated as a water temperature correction coefficient based on the water temperature. In other words, when the water temperature of the engine decreases, the exhaust pressure decreases and it becomes easier to scavenge, making it easier for fresh air to escape into the exhaust system (thus, the amount of blow-through increases. Therefore, the lower the water temperature THW, the more the correction coefficient is The value is set to be small.The memory 60-2 has a map of the water temperature correction coefficient according to the water temperature THW, and an interpolation calculation is performed on the water temperature correction coefficient for the current water temperature actually measured by the water temperature sensor 68. In step 138, the final fuel injection amount TAU is calculated by TAU=f, xKxTpxα+β.Here, α and β are representative correction coefficients and correction amounts whose explanations are omitted because they are not directly related to this invention. ing.

In step 140, it is determined whether the flag FTVIS = 1 or not.
That is, it is determined whether the intake control valve 36 is in an open state or a closed state. When the intake control valve 36 is open, the process proceeds to step 142, where TAU is entered in the address TAUa that stores the fuel injection time of the first fuel injector 38a, and TAU is entered in the address that stores the fuel injection time of the second fuel injector 38b. Zero is placed in TAUb. That is, only the first injector 38a is activated, and the second injector 38b is not activated. In step 140, the intake control valve 3
6 is closed, the process proceeds to step 144, where 1/3 of TAU is entered into the address TAUa where the fuel injection time of the first fuel injector 38a is stored, and the fuel injection time of the second fuel injector 38b is stored. Address T
The remaining 2/3 of TAU is placed in AUb. here 1
/3 and 2/3 have no specific meaning and are adaptation constants, and the effective dimension of the second intake passage Fat34b>first intake passage 3
4a, it simply indicates that the amount of fuel injected from the second injector 38b is greater than the amount of fuel injected from the first injector 38a, since the air-fuel ratio is constant in either case.

In step 146, TAUa is calculated from the expected injection start time.

Injector 38a only for a period corresponding to TAAUb.

Fuel injection signal formation processing is performed so that 38b is activated. Since this process itself is well known, detailed explanation will be omitted. Step 14B generally shows other processing that starts to be executed every time the 30° CA signal arrives.

〔Effect of the invention〕

In this invention, in an internal combustion engine such as a two-stroke internal combustion engine where fresh air often blows through, the fresh air capture coefficient is calculated using a multidimensional map according to the operating conditions of the engine, and it is corrected to the basic fuel injection amount determined by the load and rotation speed. By adding , accurate air-fuel ratio control is achieved even when the amount of fresh air blowing through varies in a complex manner depending on operating conditions, improving output, preventing overheating of the exhaust system catalyst, etc., and improving fuel consumption rate. can be achieved.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the configuration of the present invention. FIG. 2 is a schematic diagram of the entire system according to the embodiment of the present invention. Figure 3 is a diagram showing the cross section of one cylinder (m-m in Figure 2).
Figure along the line). FIG. 4 is an angle diagram of the operation timing of the intake valve and exhaust valve of one cylinder in one cycle of the engine. FIG. 5 is a diagram showing the operating timing of the exhaust valves of each cylinder in one cycle of the engine. FIG. 6 is a diagram illustrating combustion operation in one cycle of a two-stroke internal combustion engine with an intake valve and an exhaust valve according to an embodiment of the present invention under light load. FIG. 7 is a diagram illustrating combustion operation in one cycle of a two-stroke internal combustion engine with an intake valve and an exhaust valve according to an embodiment of the present invention at a time of high load. FIGS. 8 and 9 are flowcharts illustrating the operation of the control circuit. FIG. 10 is a conceptual diagram of changes in the fresh air capture coefficient fall with respect to the intake air amount-rotation speed ratio and the rotation speed. IO... Engine body 17... Combustion chambers 24a, 24b... Intake valves 26a, 26b - Exhaust valves 34a, 34b... Intake passage 36... Intake control valves 38a, 38b... Fuel injector 42 ... Inkterer 44 ... Mechanical supercharger 48 ... Air flow meter 54 ... Exhaust manifold 60 ... Control circuit 62.64 ... Crank angle sensor 68 ... Water temperature sensor Figure 1 TDC Exhaust valve closed Fig. 4 TDCBDCTDC υ Fig. 6 Exhaust Fig. 7

Claims (1)

[Scope of Claims] In an internal combustion engine such as a two-stroke internal combustion engine that has a large amount of fresh air blowing through, an air-fuel ratio control device comprising the following components: a fuel supply means for supplying a desired amount of fuel to the internal combustion engine; A fuel supply amount calculation means that calculates the fuel supply amount determined by the load of the internal combustion engine, operating conditions such as rotation speed, a storage means for storing correction factor data; interpolating a correction factor value suitable for the actually measured operating conditions of the internal combustion engine from the data stored in the storage means, and correcting the fuel supply amount calculated by the fuel supply amount calculation means; fuel supply amount modification means; means for shaping a fuel supply signal to the fuel supply means so that the modified amount of fuel is supplied to the engine;