JPS63183235A - Control device for air-fuel ratio of internal combustion engine - Google Patents

Abstract

PURPOSE:To perform accurate air-fuel ratio control irrespective of changes in scavenging characteristics by detecting temperature of emission emitted from an internal combustion engine, calculating a correction factor for compensating escape of fresh intake according to the detected value, and thereby correcting a fuel supply rate. CONSTITUTION:A 2-cycle internal combustion engine 1 or the like having a large escape ratio of fresh intake is provided with a means 2 for supplying a required rate of fuel to the engine 1 and a means 3 for calculating a fuel supply rate determined by operating conditions such as load and rpm of the engine 1. A means 4 for detecting the temperature of emission emitted from the engine 1 and a means 5 for calculating a correction factor value for compensating the escape of the fresh intake according to the detected temperature of the emission and for correcting the fuel supply rate calculated with the means 3 are also provided. A means 6 for forming a fuel supply signal to be sent to the means 2 is further provided so that a corrected rate of fuel is supplied to the engine 1.

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 also be applied to a 4-cycle internal combustion engine, such as a 4-pulp engine, which has a long valve 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. Therefore, a system is 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 solved.In other words, in a two-stroke internal combustion engine, the fresh air taken in is directly sent to the exhaust pipe without participating in total heat combustion in the cylinder bore. As a result, the amount of air in the cylinder bore that actually participates in combustion is smaller than the amount of air that passes through the engine intake system, 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 exponential function depending on the intake air amount and the engine speed.

That is, the manner in which the correction amount changes with respect to the 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 is corrected by assuming that it depends only on the amount of intake air and the engine speed. However, the change in the blow-through ratio depending on the operating conditions changes not only depending on the load and rotation speed but also on the temperature conditions of the engine, particularly the exhaust gas temperature. That is, the scavenging characteristics are affected by changes in exhaust gas temperature, and the amount of blow-through is thereby changed. In the prior art, since the correction was made only based on the load and rotational speed, it was not possible to completely compensate for blow-by, and it was not possible to accurately control the air-fuel ratio to the set air-fuel ratio.

It is an object of the present invention to accurately compensate for blow-by and to obtain a set air-fuel ratio despite changes in temperature conditions.

[Means for solving problems]

According to this invention, in FIG. 1, in an internal combustion engine in which a large amount of fresh air blows through, such as a two-stroke internal combustion engine, the air-fuel ratio control device has a fuel supply means 2 that supplies a desired amount of fuel to an inner engine 1. , a fuel supply amount calculation means 3 that calculates the fuel supply amount determined by the load of the internal combustion engine and operating conditions such as the rotation speed, an exhaust gas temperature detection means 4 that detects the temperature of exhaust gas from the internal combustion engine, and an exhaust gas temperature detection means 4 that detects the temperature of the exhaust gas from the internal combustion engine. Fuel supply amount correction means 5 calculates a correction factor value for compensating for blow-through according to the exhaust gas temperature detected by the gas temperature detection means 4, and corrects the fuel supply amount calculated by the fuel supply amount calculation means 3; , means 6 for controlling the fuel supply signal to the fuel supply means so that the corrected amount of fuel is supplied to the engine.

[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 correction factor according to the exhaust gas temperature detected by the exhaust gas temperature detection means 4. is calculated, the fuel supply amount calculated by the fuel supply amount calculation means 3 is corrected according to the fresh air blowing, and the fuel supply signal forming means 6 is configured to send the fuel supply amount to the fuel supply means 2 so as to obtain the corrected fuel supply amount. form a signal.

〔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-valve type two-stroke internal combustion engines. Further, even in a 4-cycle internal combustion engine, the idea of the present invention can be applied to a 4-pulp type engine in which the valve overlap period is long and there is a lot of blow-by of intake air. In Fig. 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 bows 1-20a, 20
b.

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

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 having an intake bow 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. Reed valves 40a and 40b are installed as necessary to control backflow.

An ink cooler 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 adjusts 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 group #l~#3, #4
The exhaust manifolds 54 of the cylinder groups #6 to #6 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 (MPU) 60-1, a memory 60-2, input ports 0-3, output ports 0-4, and a bus 60-5 connecting these. Input Portro 0-
Each sensor is connected to 3, and an operating condition signal is inputted thereto. The air flow meter 48 may be of a volumetric flow rate type, and measures the flow ff1Q 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 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. The pressure sensor is installed in the bypass passage 44.
In this embodiment, it is preferable to install the bypass passage 44' upstream of the connection point of the bypass passage 44' so that the pressure is not affected by the bypass air flow rate. If the supercharging system does not include a bypass, it is also possible to install a pressure sensor downstream of the supercharger. Crank angle sensor 6
2,64 are installed in the distributor 58. 1st
The crank angle sensor 62 is connected to the distributor shaft 58.
It is installed facing the magnet piece 58-2 fixed on the top of the magnet 58-1, and generates a pulse signal every 360 degrees of crank angle (corresponding to one cycle of the engine), for example, 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. An exhaust gas temperature sensor 68 is installed in the exhaust manifold 54 near the exhaust bows 22a and 22b, and obtains a signal corresponding to the temperature TAX of exhaust gas discharged from the engine.

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 the actuator 37 and the fuel injector 3 of each cylinder.
8a and 38b, 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 80 degrees before bottom dead center (BDC) and end closing 40 degrees after bottom dead center (BDC). On the other hand, the intake valves 24a and 24b are at 60° before the bottom dead center (B D C).
It starts opening at 60@ after bottom dead center (BDC) and finishes closing.

Note that ■ indicates the fuel injection period. FIG. 5 is a timing diagram showing the operating period of the exhaust valve in each cylinder with respect to the crank angle. Since it is a 2-cycle engine, 36
At 0'CA - the cycle is completed and, according to the firing order, the exhaust valve is activated for the period E shown in FIG.
The valve is opened over X. For a group (#1 to #3 or #4 to #6) of every other cylinder in the firing order, the exhaust valve is opened every 120 degrees, and in each group, the cylinders adjacent to each other in the firing order are opened every 120 degrees. The opening periods of the exhaust valves are set so as not to overlap each other. - 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 to prevent this from occurring, as it may have an adverse effect on the operation of accurately compensating the air-fuel ratio according to the amount of air blow-through, which will be described later. On the other hand, including the two groups, the opening period of the exhaust valve overlaps between cylinders with adjacent ignition orders, but since the exhaust manifold 54 is different 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. In the process of lowering the piston 16, the exhaust valves 26a, 26 first close to 80 degrees before bottom dead center (BDC).
b begins to open.

Therefore, the exhaust gas from the combustion chamber moves to arrow P in Figure 6 (a).
As shown in the figure, the air is discharged to the exhaust ports 22a and 22b, causing so-called blowdown, but this blowdown is weak and ends quickly.

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, and when the piston 16 further descends, the cylinder bore Since there is a weak negative pressure inside the cylinder 14, the pressure difference between the exhaust bows 22a and 22b causes the exhaust gas to flow back toward the cylinder bore as shown by the arrow Q (FIG. 6(b)). 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, and the intake passage 34b, which has a large effective dimension, is closed and the effective dimension Due to the fact that air can flow only through the small intake passage 34a, the introduction of fresh air does not substantially occur. As the piston 16 further descends, the exhaust gas continues to swirl, 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 exhaust gas R and fresh air S is maintained even when the piston reaches bottom dead center (BDC) (see Fig. 6).
d)). (E) Intake valve 24a.

24b is 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 fresh air 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 to the exhaust port 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 point in FIG. 7(c), a negative pressure component in the pressure wave pulse due to strong blowdown appears, and the exhaust bows 22a and 22b temporarily become negative pressure, resulting in the introduction of fresh air T into the cylinder bore further. Some of the fresh air flows out into 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. If FTVIS = 0, step 10
2, the intake air amount to revolution speed ratio Q/NE is set to a predetermined value (1
1/Nu).

It is determined whether the rotation speed NB is larger than the predetermined value (NE) in step 104. 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 (N li ). In this case, the process proceeds to step 106, where a signal for causing the actuator 37 to open the intake control valve 36 is outputted from the output ports 0-4. At step 108, the flag FTVIS=1 is set. When FTVIS = 1, step 110
Then, the intake air amount to revolution speed ratio Q/NE is set to a predetermined value (Q/NE).
IJE) It is determined whether or not it is smaller than I, and step 11
In step 2, it is determined whether the rotational speed NE is smaller than a predetermined value (NE)l. Intake air amount to rotation speed ratio Q/NE < predetermined value (G/NE) + and rotation speed ME < predetermined value (NE)
If it is +, proceed to step 114 and output port 〇-
4 outputs a signal to the actuator 37 to close the intake control valve 36. In step 116, the flag FT
VIS = O is set.

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, this embodiment also measures the amount of intake air in principle and injects the amount of fuel according to the measured value to obtain the desired air-fuel ratio. This is what we are trying to do. However, similar problems exist in ordinary piston pulp 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. The proportion of fresh air that blows through changes in a complex manner depending on the load, rotation speed, and other operating conditions. Therefore, in this embodiment, data on fresh air capture coefficients corresponding to a plurality of operating conditions are stored in the memory 60-2, and the fresh air capture coefficients are calculated by interpolation during actual driving. By correcting the fuel injection amount, it is intended that the desired air-fuel ratio can be obtained even if the blow-through ratio changes depending on the operating conditions.

However, the blow-through ratio is affected by temperature conditions, especially exhaust gas temperature, in addition to load and rotation speed. That is, the pressure of the exhaust gas changes depending on the exhaust gas temperature, which affects the scavenging characteristics. Therefore, in the present invention, it is possible to accurately control the air-fuel ratio to the target by adding correction based on the exhaust gas temperature. FIG. 9 shows a 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. Step 130
Then, it is determined whether or not the fuel injection calculation timing is reached.

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 from the first crank angle sensor 62.
6o.

Cleared by the CA double signal, the second crank angle sensor 6
This can be known from the value of the counter that is incremented by the 30° CA signal from 4.

If it is determined that it is the fuel injection calculation timing, step 132
, the basic fuel injection ff1Tp is Tp=k (Q
'/NE). Here, Q' is the intake air amount Q 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. (Intake pipe pressure P
In a system in which the fuel injection amount is determined by M, PM can be used instead of Q'/NEO. ) step 134
Then, a map calculation of the fresh air capture coefficient fTll is executed.

Here, the fresh air capture coefficient fT11 is the air flow meter 48.
This is a fuel injection amount correction factor related to the proportion of fresh air that actually participates in combustion within the cylinder pore, which is calculated by subtracting the amount of fresh air that has flowed out into the exhaust system due to blow-through from the intake air amount measured by . FIG. 10 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 due to the influence of pressure pulsations in the exhaust pipe due to blowdown, etc., the intake air amount changes in a complex manner with respect to the rotational speed ratio and the rotational speed (the case where there is no influence due to 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 r□ changes discontinuously at the boundary (see the two-dot chain line). Memory 60-
2 stores the data of the fresh air capture coefficient fTR for the combination of intake air amount/rotation speed ratio and rotation speed according to FIG. 1θ. 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 fTR that is suitable for the current operating conditions is calculated.

In addition, in a system that determines the fuel injection amount based on the intake pipe pressure P'M, the fresh air capture coefficient f is determined based on the combination of PM and rotation speed.
A TII map is assembled, and an interpolation calculation is performed based on the intake pipe pressure actually measured by the pressure sensor 60. In addition, in the embodiment, the basic fuel injection is calculated first, and the fresh air capture coefficient f is added to the basic fuel injection.
Although the correction is performed by multiplying by T11, the basic fuel injection amount may be calculated by first adding correction by the fresh air capture coefficient fTll to the intake air amount and then calculating the basic fuel injection amount from the corrected intake air amount.

In step 136, a correction coefficient for the fresh air capture coefficient fT11 is calculated based on the exhaust gas temperature T[X.

That is, as the exhaust gas temperature increases, the pressure of the exhaust gas increases, making it difficult to scavenge, which becomes a factor in reducing the amount of blow-through. Therefore, the fresh air capture coefficient fall is multiplied by the correction coefficient K, which increases as the exhaust gas temperature T- increases, to realize accurate compensation of the air-fuel ratio in relation to the exhaust gas temperature. The memory 60-2 has a map of exhaust gas temperature correction coefficients according to the exhaust gas temperature T-, and interpolates the exhaust gas temperature correction coefficient for the current exhaust gas temperature T- actually measured by the exhaust gas temperature sensor 68. The operation is executed. In step 138, the final fuel injection amount TAU is determined as TAU=f
It is calculated by t*XKXTpX(r+β. Here, α and β are typical correction coefficients and correction amounts whose explanations are omitted because they are not directly related to the present invention.

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, and TAU is stored in the address TALJa for storing the fuel injection time of the first fuel injector 38a.
is entered, and zero is entered into the address TAUb that stores the fuel injection time of the second fuel injector 38b. That is, only the first injector 38a is activated, and the second injector 38b is not activated. When the intake control valve 36 is closed in step 140, the process advances to step 144, where 1/3 of TAU is entered into the address TAUa storing the fuel injection time of the first fuel injector 38a, and The remaining two-thirds of the TAU is stored in the address TAUb that stores the fuel injection time. Here, 1/3 and 2/3 have no specific meaning, but are adaptation constants, and since the effective dimension of the second intake passage 34b>the effective dimension of the first intake passage 34a, the air-fuel ratio can be set either way. Since it is constant, it merely 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.

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

Injectors 38a and 38b only for a period corresponding to TAUb
A fuel injection signal forming process is performed so that the fuel injection signal is activated.

Since this process itself is well known, detailed explanation will be omitted. Step 148 generally shows other processing that is started to be executed each time the 30° CA signal arrives.

〔Effect of the invention〕

In an internal combustion engine such as a two-stroke internal combustion engine where there is a lot of fresh air blow-through, this invention compensates for the blow-through according to the exhaust gas temperature to maintain an accurate air-fuel ratio even if the scavenging characteristics change due to changes in the exhaust gas temperature. control is realized, and it is possible to improve output, prevent overheating of the exhaust system catalyst, etc., and improve fuel consumption rate.

[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. FIG. 3 is a diagram showing a cross section of one cylinder (a diagram taken along the π-di line in FIG. 2). 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 fTR with respect to the intake air amount-rotation speed ratio and the rotation speed. 10... 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...Intercooler 44...Mechanical supercharger 48...Air flow meter 54...Exhaust manifold 60...Control circuit 62.64...Crank angle sensor 68...Exhaust gas temperature sensor

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; Fuel supply amount calculation means that calculates the fuel supply amount determined by the load of the internal combustion engine and operating conditions such as rotation speed; Exhaust gas temperature detection means that detects the temperature of exhaust gas from the internal combustion engine; Exhaust gas temperature detection means detects fuel supply amount correction means for calculating a correction factor value for compensating for blow-through according to the exhaust gas temperature to correct the fuel supply amount calculated by the fuel supply amount calculation means; Means for shaping the fuel supply signal to the fuel supply means to be supplied to the engine.