JPS63208674A - Ignition timing controller for two cycle internal combustion engine - Google Patents

Abstract

PURPOSE:To secure the stable combustion operation of an engine and improve fuel consumption rate by controlling the ignition timing so as to be corrected to the reduction direction of misfire, when misfire is detected from the exhaust pressure, etc. CONSTITUTION:The ignition timing is calculated in an ignition timing calculating means 2 on the basis of the operation conditions such as the load Q/NE of an internal combustion engine and the number of revolution NE, and the output signals are sent into an ignition signal generating means 3. The ignition signals which are formed so that the independent ignition timing for each cylinder can be obtained are applied into an ignitor 1A, and fuel is ignited at the proper timing in each cylinder. In this case, a misfire detecting means 4 for detecting the misfire state in ignition is installed independently in each cylinder. When misfire is detected, an ignition timing correcting means 5 corrects the ignition timing calculated by the ignition timing calculating means 2 to the reduction direction of misfire.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an ignition time control roller device suitable for a two-stroke internal combustion engine.

[Conventional technology and problems]

In a two-stroke internal combustion engine, it is difficult to completely scavenge air, especially during low load such as idling, and a considerable amount of exhaust gas remains in the cylinder bore along with fresh air. Therefore, there are many misfires. Therefore, the ignition timing is set to a fixed value that is retarded from the optimum ignition timing (MBT).

However, misfire conditions vary considerably depending on operating conditions, and in order to prevent misfires from occurring under any assumed operating conditions, it is necessary to set a considerably large retard angle setting value. However, there is a problem that increasing the retard angle ν deteriorates the fuel consumption rate.

An object of the present invention is to provide an ignition timing control system; η that can control the ignition timing to a value as advanced as possible within a range where misfire does not occur in a two-stroke internal combustion engine.

Incidentally, related art to the present invention, which relates to an ignition time control '41'J device for a four-stroke internal combustion engine, is disclosed in Japanese Patent Publication No. 59-32659 and Japanese Patent Application Laid-Open No. 58-62374.

[Means for solving problems]

The ignition timing control device for a two-stroke multi-cylinder internal combustion engine of the present invention includes means 2 for calculating the ignition timing determined by the operating conditions of the engine l, and an ignition system IA for obtaining the ignition timing calculated by the ignition timing calculation means 2. An ignition signal forming means 3 for forming an ignition signal, a misfire detecting means 4 for detecting whether or not a misfire has occurred at each ignition time, and an ignition timing calculating means 2 for reducing the number of misfires when a misfire is detected. It is comprised of an ignition timing correction means 5 for correcting the calculated ignition timing.

(Example) FIG. 2 shows the overall schematic structure 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. 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 1G, a combustion chamber 17,
It includes a cylinder head 18 and a spark plug 19. The cylinder head 18 has two intake boats 20a, 20b and two exhaust ports 22a.

22b, intake valves 24a, 24b and exhaust valves 26a, 26b for opening and closing the respective intake boats and exhaust ports.
It is a so-called 4-valve type.

The intake valve and the υ intake valve are driven to open and close by dedicated cams 27 and 28, respectively. 30.31 is a valve spring. When exhaust gas flows back into the cylinder bore due to negative pressure after blowdown, the exhaust boats 22a and 22b
The shape is selected to provide a swirl of the exhaust gases within the cylinder bore about its vertical axis.

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, respectively.
, 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 that operates under negative pressure, and is switched between negative pressure and atmospheric pressure by a switching valve (not shown), and the intake control valve 36 has a position where it opens the intake passage 34b and a position where it closes it. can be taken selectively. 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 the 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 constituted by, for example, a roots pump or a vane pump, and has a pulley 44-2 on its drive shaft 44-1, and is connected to a pulley 15' on the crankshaft 15 by a belt 44-3. Mechanical supercharger 4
A bypass control valve 45 is provided in the bypass passage 44' that bypasses the
is installed and plays the role of adjusting the intake pipe pressure. In this embodiment, the ink cooler 42 is configured as an air-cooled type, and includes an artificial container 42-1, an outlet container 42-2,
A heat exchange tube 42-3 communicating therebetween, and a heat exchange tube 42-
3 and fins 42-4 attached on top of the fins 42-4.

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 engines with alternating ignition, the exhaust pressure of one cylinder during the scavenging stroke is not affected by the exhaust pressure of other cylinders. The exhaust manifolds 54 of cylinder groups #1 to #3 and cylinder groups #4 to #6 are each equipped with a dedicated catalytic converter (
55 (which may also be used as a muffler or a dedicated muffler may be installed separately).

A distributor 58 is connected to the spark plug 19 of each cylinder via an ignition device 59, and ignites at a desired crank angle. The ignition device 59 is an igniter 59-1
and an ignition coil 59-2.

The control circuit 60 controls the formation of an ignition signal to the ignition device 59 so as to obtain a desired ignition timing according to the present invention, and performs other fuel injection control and intake control valve control, and is implemented as a microcomputer system. configured. The control circuit 60 includes a microprocessing unit (M
PU) 60-1, memory 60-2, input port 0
-3, output capo-1-G O-4, and a bus 60-5 connecting these. Irikapo-1-60-3
Each sensor is connected to the , and operating condition signals are input manually.

The air flow meter 48 may be of a volume flow Y 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 is installed, for example, downstream of the throttle valve 46 and upstream of the supercharger 44, and generates a signal corresponding to the intake pipe pressure PM. A crank angle sensor 62.degree. 64 is installed on the distributor 58. The first crank angle sensor 62 is installed facing the magnet piece 58-2 fixed on the distributor shaft 58-1, and generates a pulse signal every 3600 crank angles (corresponding to one engine cycle), for example, and generates a reference signal. It becomes a signal. On the other hand, the second crank angle sensor 64 is connected to the distributor shaft 58-1. It is installed facing the magnet piece 58-3 of the engine, and generates a pulse signal every 30 degrees of the crank angle, for example, so that the engine rotation speed can be determined, and it also serves as a start signal for the fuel injection routine.

According to this invention, an exhaust gas pressure sensor 65 is provided, and misfire can be detected independently for each cylinder based on the exhaust gas pressure, as will be described later. A communication pipe 63 with a small diameter is provided to connect the two groups of exhaust manifolds 54, and a pressure sensor 65 detects the presence or absence of blowdown from the peak position of the pressure waveform obtained by averaging the exhaust gas pressures in the two exhaust manifolds 54. It is possible to know whether there is a misfire or not. Note that by narrowing the diameter of the communication pipe 63, the independence of the pressures within the two exhaust manifolds 54 can be made unaffected. The pressure sensor 65 has an integral circuit 66
, is connected to a peak hold circuit 67, the integrating circuit 66 detects the average value of exhaust gas pressure fluctuations, the peak hold circuit 67 detects the peak of the exhaust gas pressure, and the presence or absence of a misfire can be determined from the magnitude of the peak value. It is. Integrating circuit 66 has a time constant that allows it to detect a hackground value in the output from pressure sensor 65. The peak hold circuit 67 can sequentially update the peak value of the signal from the pressure sensor 66 for each combustion, and can be reset by an external signal.

The MPU 60-1 executes arithmetic processing according to the program and data stored in the memory 60-2, and operates the igniter 5.
9-1, other engine control devices such as the intake control valve actuator 37 and the injector 38a,
38b and the like is executed. Output port 0-4 is igniter 59-1. Actuator 37
It is connected to the 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 exhaust valves 26a, 2'6b begin to open at an angle of 80 degrees before bottom dead center (BDC).
) and finishes closing at 40°. On the other hand, the intake valves 24a and 24b
starts opening 60” before bottom dead center (BDC), and
DC) and ends at 60'' after bottom dead center (TDC). ■ indicates the fuel injection period, which starts 20 degrees after bottom dead center (B D C) and ends just before the intake valve closes. ), the angle SA from top dead center is changed depending on the operating conditions as is well known, and according to the present invention, the ignition timing is corrected depending on the presence or absence of misfire.

Next, 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 flows from the combustion chamber to arrow P in Figure 5 (a).
The air is discharged to the exhaust boats 22a and 22b, causing so-called blowdown, but this blowdown is weak and ends quickly. 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 boats 22a and 22b causes the exhaust gas to flow back toward the cylinder bore as shown by arrow Q (see Fig. 5). )
).

Because of the shape of the exhaust boats 26a and 26b, a swirl of exhaust gas as shown by arrow R is formed within the cylinder bore. At this time, 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.
Due to the fact that air can flow only through the intake passage 34a, which has a small effective dimension, substantially no fresh air is introduced. When the piston 16 further descends, the swirl of exhaust gas continues, while the lift of the intake valves 24a and 24b increases, so fresh air is introduced into the cylinder bore as shown by arrow S.
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 collects near the spark plug electrode above the swirled exhaust gas part (Fig. 5 (c)). ) a good stratification is achieved. This stratified state of exhaust gas R and fresh air S is maintained even when the piston reaches bottom dead center (BDC) (Figure 5 (d)).
). In (E), the intake valves 24a and 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, and ignition is performed at an angle of SA just before top dead center, making it easy to ignite the fresh air near the spark plug. Can be done.

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. 6, 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 (Figure 6 (a)) than when the load is light.
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. It will be held on. 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 port 22a as shown by arrow U. , 22b, so-called cross-scavenging air is realized. At the point in Figure 6 (c), a negative pressure component appears in the pressure wave pulse due to strong blowdown,
The exhaust ports 22a and 22b temporarily become negative pressure, and as a result, the introduction of fresh air T into the cylinder bore is further promoted, and some of the fresh air temporarily flows out to the exhaust ports 22a and 22b and is stored as shown in (3). . This stored fresh air is delivered 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. 6 (d)). This causes turbulence and improves flame propagation after ignition. At the time of FIG. 6(E), the intake valve 24a
, 24b completes the closure and fresh air is prevented from blowing back. Then, it is ignited just before compression top dead center.

Next, a control circuit 60 for performing ignition control according to the present invention
The operation will be explained using a flowchart. The fuel injection control and the control of the intake control valve 36 are not directly related to the present invention, so their explanation will be omitted. FIG. 7 shows the misfire determination routine, FIG. 8 shows the ignition timing side i1j routine, and FIG. 9 shows the initialization part of the main routine. In the routine shown in FIG. 7, misfire is detected for each cylinder based on the change in exhaust gas pressure from the pressure sensor 65. To first explain the principle of determining a misfiring cylinder based on a change in exhaust gas pressure, the pressure inside the pipe 63 where the pressure sensor 65 is installed is determined by averaging the pressures of the two exhaust manifolds 54, as shown in Fig. 10 (a). Changes to The peak corresponds to a blowdown, assuming there is no misfire.
In a 6-cylinder, 2-stroke internal combustion engine, this occurs every 60° CA. However, if there is a misfire, no blowdown occurs, so the pressure hardly peaks. In Figure 10, #6. 2. This indicates that there was a misfire in the No. 5 cylinder. Therefore, by detecting the presence or absence of a peak in exhaust gas pressure, it is possible to know whether a misfire has occurred.

In this embodiment, the peak of the pressure signal is extracted by a peak hold circuit 67, and the presence or absence of a misfire is determined by comparing this peak value with a bank ground value extracted by an integrating circuit 66. And, in an embodiment of this invention,
The misfire rate is determined by calculating the ratio of the number of misfires to the total number of ignition ports using a predetermined arithmetic formula, and the ignition timing is controlled in a direction that reduces this misfire rate. The routine shown in FIG. 7 is located in the middle of a crank angle interrupt routine executed by the arrival of crank angle pulses every 30 degrees from the second crank angle sensor 64.

In steps 100 and 102, it is determined whether or not the engine operating range is where the misfire determination according to the present invention is performed.

At step 100, the engine speed NE is (NE), <N
It is determined whether E<(NE)2. Here, (NE)+ is a value of about 400rpm, for example, and (NE)2 is -1000r
It is a value of pm. In step 102, it is determined whether the intake air amount to revolution speed ratio Q/NE<predetermined value (Q/NE)+. When the engine is at high speed and high load, the exhaust gas pressure fluctuates greatly, making it difficult to accurately detect a misfire.Since misfires almost never occur, the misfire detection routine is bypassed. Furthermore, when the engine speed is extremely low, the exhaust gas pressure peak is small and the determination accuracy is reduced, so the misfire determination routine is similarly bypassed. When bypassing the misfire determination routine, the process proceeds to step 104, where the ignition timing control cancel flag FX'=1 and the ignition timing retardation correction amount Δ5A=0. The flag FX' is used to bypass the ignition timing control according to the misfire rate at the time of cent.

If it is in the misfire discrimination range, the process proceeds from steps 100 and 102 to step 108, where the misfire discrimination stop flag FX' is set to O. Therefore, the ignition timing is controlled according to the misfire rate (see step 136 in FIG. 8). Step 11
At 0, it is determined whether it is the timing for sampling the peak pressure in the exhaust gas pressure. This timing is set slightly later than when the pressure peak due to blowdown is obtained. In other words, blowdown occurs every 60° CA in a 6-cylinder internal combustion engine, so the law (
It can be determined whether the timing is right or not based on the number of 30° pulses from the 1-loss crank angle. If it is determined that it is the timing for sampling the peak pressure, the process proceeds to step 112, where it is determined whether the peak pressure P pesh>kxp□. P here. 7 is the time average value (bank ground level) of the pressure signal level of the pressure sensor 65 known by the integrating circuit 66. k is a suitable constant. When pressure is generated due to blowdown, P peak >k
×P maa. Therefore, it is recognized that there was no misfire, and the process proceeds to step 114, where the misfire rate is calculated by the following formula: R,l is the value of R5 obtained when this routine was executed last time. When no blowdown occurs, P peak≦k X [). , becomes 7,
It is recognized that a misfire has occurred, and the process proceeds to step 116, where the misfire rate is calculated by the following formula: R,=((N-1)R,'+1)/N. The above two equations are expressed as follows: The previous value R1 is N-
A weight of 1 is attached, and the current value is given a weight of 1. By selecting the (direction) of N to i4η, it is possible to make it a value that represents the number of misfires out of all the ignitions. In other words, 1 is the change in R due to - misfires.
/N can be made to correspond to a change in misfire rate. For example, a value of about 10 is appropriate for N at startup, and N at room temperature.
A value of about 50-100 is appropriate.

In step 11B, the value of R1 is set to R, l for the next processing.
can be placed in In step 120, the peak hold circuit 67 is reset (R3 in Figure 1O (c)).
, the peak hold circuit 67 starts holding the pressure peak by blowdown of the next cylinder. As described above, by detecting the exhaust gas pressure using the routine shown in FIG. 7, it is possible to know the misfire rate over all cylinders.

FIG. 8 shows an ignition timing control routine, and like the routine shown in FIG. positioned. In step 130, it is determined whether or not it is the ignition calculation timing. As shown in FIG. 4, fuel injection is performed in a predetermined crank angle range slightly before top dead center TDC, so this calculation is executed at a predetermined crank angle slightly prior to top dead center TDC.

This timing is based on the 3rd angle signal from the first crank angle sensor 62.
This can be determined by the value of a counter that is cleared by the 60° CA signal and incremented by the 30° CA signal from the second crank angle sensor 64. If it is determined that it is the ignition timing calculation timing, the process proceeds to step 132, where the basic ignition timing 5AIASE is calculated from the intake air amount-to-rotation speed ratio Q/NE as a load factor and the rotation speed NE.

Here, the basic ignition timings 5AllA and E are the ignition timings (MBT) at which maximum torque is obtained at the given load and rotational speed. The memory 60-2 has a map of 5AIASE data for combinations of intake air amount, rotational speed ratio, and rotational speed.
The PU 60-1 executes an interpolation calculation to obtain the values of the SA port and E for the current intake air amount-to-rotation speed ratio and the rotation speed. In step 134, it is determined whether the flag FX=1, and in step 13G, it is determined whether the flag FX'=1.

These are set when the conditions are met to exit the misfire determination/retard amount control routine from step 138 onwards. When flags FX and FX' are both reset, step 13
8, it is determined whether the misfire rate R1 obtained in steps 114 and 116 in FIG. 7 is greater than a predetermined value A. FIG. 11 is a graph schematically showing the relationship between the advance angle and the misfire rate, and the predetermined value A is set at a point where the misfire rate starts to increase suddenly.

If the misfire rate R is set to a predetermined value A in step 13B, the process proceeds to step 140, where the ignition timing retardation correction amount ΔSA is decremented by α, and if the misfire rate R0≧predetermined value A,
The process proceeds to step 142, where the ignition timing retardation correction amount ΔSA is incremented by β. ΔSA is the basic ignition timing 5
This is the amount of correction on the retard side for AllAsE. Therefore,
If the misfire rate is large, the ignition timing will be adjusted to the retarded side, and if the misfire rate is small, the ignition timing will be adjusted to the advanced side, thereby trying to maintain the misfire rate at about . be.

After step 142 of retarding the ignition timing, the routine of steps 143 to 150 determines whether the misfire rate is actually reduced by retarding the ignition timing. In step 14B, the counter n is incremented. This counter n measures the number of ignitions after starting the retard process, and its initial value is zero. In step 144, it is determined whether the counter n=1, that is, whether or not it is the ignition time when the retard process has started. When n=1, the process proceeds to step 145, and the value of the current misfire rate R1 is stored in the address RpaN that stores the misfire rate at the start of the retard process.

If n≠1 in step 144, the process proceeds to step 146, where it is determined whether the value of the counter n has reached the number N of ignitions to be waited for in order to see the change in the misfire rate after the retard process.

If NO, exit from the following routine 148.150. If YES in step 146 and N ignitions have been performed after the first retard process, the process proceeds to step 148, where the counter n is cleared, and in step 150, the current misfire rate R1,! : It is determined whether the difference from the misfire rate R□ N times before (step 14 et al.) is smaller than a predetermined small value δ, that is, whether the misfire rate has been reduced by retarding the ignition timing.

If the misfire rate is actually controlled to be small by the retard process, the process proceeds to steps 152 and 154, where it is determined whether the retard correction amount ΔSA has reached its maximum value ΔSAMAX, and it is determined that ΔSA≧ΔSAMAX. Guard processing is performed to prevent exceeding the limit. Similar go 1 processing is also performed in step 156.15 when advance angle processing (step 140) is performed.
8, and the retard angle correction amount ΔSA is the minimum value Δ5A.
Guard processing is performed so that the value does not become smaller than 0.

In step 154, if the misfire rate is not reduced despite the retardation process, the process proceeds to step 160, where the flag FX=1 is set, and the control is stopped.
Proceed to step 162 and retard correction term ΔSA - predetermined value ΔS
A o is fixed. Instead of fixing the amount of retardation, it is also possible to simply adjust the control. It is also possible to use a logic that limits the suspension of control jJ■ to a predetermined time.

In step 162, the final ignition time yIISA is determined by subtracting the retardation correction amount ΔSA from the basic ignition timing 5A11A52. In step 164, a well-known ignition signal formation process is performed, and an ignition signal is applied to the igniter 59-1 so that ignition is executed at an angle of SA as measured from TDC.

FIG. 9 shows an initialization portion related to the present invention of the main routine of the control circuit that is activated by turning on the ignition switch. In step 170, the flag F
X and FX' are reset, a counter n is cleared in step 170, and an initial value R1° is entered in the misfire rate R7 in step 172. Step 150,1 in FIG.
If the misfire rate does not decrease at 60 regardless of the retard control, the till control will be canceled (FX=1), but once the engine is turned off and restarted, it will be initialized.

FIG. 12 schematically explains ignition timing control according to the present invention. When a misfire occurs, the retard angle correction amount ΔSA is increased by β as shown in (a). As a result, when the misfire rate R0 actually decreases as shown by the solid line in (b) and becomes equal to or less than the predetermined value A, the retard angle correction amount ΔSA is decreased by α. If the misfire rate does not decrease during N ignitions (c) despite retardation of the ignition timing as shown in the dashed-dotted line in (b), the flag FX is set as shown in the dashed-dotted line in (d). , the control is stopped and the retard angle correction amount is fixed at ΔSA.

〔Effect of the invention〕

According to this invention, a misfire is detected from exhaust gas pressure, etc.
By retarding the ignition timing and observing changes in the misfire rate, it is possible to ascertain whether misfires are actually decreasing, and thereby control the ignition timing in a direction that suppresses misfires. In this way, it is possible to position the ignition timing on the advanced side while suppressing misfires as much as possible, and it is possible to reconcile the contradictory requirements of stable combustion operation of the engine and 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. Figure 3 is a diagram showing a cross section of one cylinder (I[[ in Figure 2
-111 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 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. 6 is a diagram illustrating the combustion operation in the entire engine 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. 7, 8, and 9 are flowcharts illustrating the operation of the control circuit. FIG. 10 is a time-lapse diagram illustrating exhaust gas pressure, average value, peak value, and peak pressure sampling timing. FIG. 11 is a graph illustrating a schematic relationship between advance angle ■ and misfire rate. FIG. 12 shows the misfire rate, counter value n, and
FIG. 3 is a timing diagram illustrating changes in flag FX. IO...engine body 17...combustion chamber 19...ignition plugs 24a, 24b...-intake valves 26a, 26b...-exhaust valves 34a, 34b...intake passage 36...intake control valve 38a , 38b... Fuel injector 42... Ink meter 44... Mechanical supercharger 48... Air flow meter 54... Exhaust manifold 59... Ignition device 59-1... Igniter 59-2 ...Ignition coil 60...Control circuit 62,64...Crank angle sensor 65...Exhaust gas pressure sensor Fig. 3 Fig. 4 - Fig. 5 Exhaust Fig. 6

Claims (1)

[Scope of Claims] An ignition timing control device for a two-stroke multi-cylinder internal combustion engine comprising the following components: means for calculating the ignition timing determined by the operating conditions of the engine; ignition signal forming means for forming an ignition signal in the ignition device at each ignition; misfire detection means for detecting whether or not a misfire has occurred at each ignition; and ignition timing calculation means for calculating the ignition timing in a direction in which the number of misfires is reduced when a misfire is detected. Ignition timing correction means for correcting the ignition timing.