JPS62147050A - Ignition control device for two-cycle internal combustion engine - Google Patents

Abstract

PURPOSE:To save electric discharge energy and prevent the wear of the electrode of an ignition plug by stopping the electric discharge of the ignition plug when an engine has been judged to be over a predetermined temperature level and below a predetermined load. CONSTITUTION:A micro computer 80 judges from the outputs of an exhaust gas temper ature sensor 15 and a water temperature sensor 40, whether exhaust gas and water temperature is in a warming-up condition over a certain temperature level, when an engine has been judged as not in a starting condition from the signal of a starter switch. If the engine is in a warming-up condition, the micro computer 80 calls in a spark ignition zone as predetermined by the map of the number of engine revolutions and engine loads. And when a condition is outside the spark ignition zone, the condition is judged as in a complete self-ignition operation zone and spark ignition with an ignition plug 7 is stopped. In an operation zone wherein self-ignition is difficult, includ ing starting, warming-up and high-load conditions, a spark occurs in the gap of the ignition plug 7, when an electrically live advance control signal has been transmitted from the micro computer 80 and an ignition signal has been given to a high voltage generator 110.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a two-stroke internal combustion engine, and particularly to a self-ignition region that can ignite without the discharge of a spark plug, and a method for starting, warming up, and under high load. The present invention relates to an ignition control device for a two-stroke internal combustion engine that has an operating region in which self-ignition is difficult.

[Conventional technology]

Two-stroke internal combustion engines are already known, which flow fresh air into the cylinder at low speed mainly during light loads and high rotations, stratify it with high-temperature exhaust gas, and adiabatically compress it during the compression stroke to produce self-ignition combustion. (For example, Tokuko Sho 58-455
No. 76).

[Problem that the invention seeks to solve]

As mentioned above, in a two-stroke internal combustion engine that has a self-ignition region in frequently used operating ranges, if a spark plug is used to discharge sparks over the entire operating range, there will be a loss of discharge energy and wear and tear on the spark plug electrodes. Also, if you try to continue or stop the spark discharge depending on the operating range, it is difficult to judge whether or not to stop the discharge, and if the spark discharge is stopped when it is not in the self-ignition range, it will cause a misfire and the engine This causes problems such as stopping.

[Means for solving problems]

In order to solve these problems, the present invention provides a complete self-ignition operation range in which the ignition can be ignited without the need for discharge from the ignition plug, and a complete self-ignition operation range in which the ignition is difficult, such as during starting, warming up, or under high load. In a two-stroke internal combustion engine that has a
An ignition control system for a two-stroke internal combustion engine that, when it detects that a frequently used engine is above a certain temperature and below a certain load, assumes that the engine is in the fully self-ignition operating range and stops discharging the spark plug. is provided.

[For production]

According to the present invention, since the spark ignition of the ignition plug is stopped in the frequently used completely self-ignition region, discharge energy is saved and the electrodes of the ignition plug are prevented from being worn out.

〔Example〕

Hereinafter, the present invention will be described in detail based on embodiments with reference to the accompanying drawings.

FIG. 1 is a diagram showing the configuration of a control unit.

10 is a known crank angle sensor for detecting changes in crank angle position, 2 revolutions, and 2 revolutions; 20 is a known starter switch for detecting when starting; 40 is a known water temperature for detecting warm-up state. Sensors 50 are known exhaust temperature sensors that detect warm-up conditions and combustion conditions; 60 are known throttle valve opening sensors that detect throttle opening and rapid changes (transient conditions); and 70 are intake air flow rate and 80 is a microcomputer (ECU) for operating the control system based on a predetermined procedure; 90 is a combustion pressure sensor for detecting the combustion state; 100 is a known air flow meter for detecting the load state; A known fuel injection control section 110 that controls the amount of fuel depending on the operating state is a known energization advance angle control section and high voltage generator that controls the energization advance angle according to the operating state.

FIG. 2 is a configuration diagram for detecting combustion pressure, and FIG. 3 is a timing chart for detecting combustion pressure.

Acupressure gauges 91a, 9 installed in the combustion chamber of each cylinder (this example will be explained using a 4-cylinder engine) to measure combustion pressure.
The outputs of 1b, 91c, and 91d are the charge amplifier 92.
The load is input to a voltage, which is then converted into a voltage and further amplified.

The output of the charge amplifier 92 is sent to the analog multiplexer 9.
3 is input. The analog multiplexer 93 is an EC
The shiatsu meter 91a is controlled by the timing control signal input from U3O.

The signals from 91b, 91C, and 91d are switched to take in the combustion period signal of each cylinder. The output of the analog multiplexer 93 is input to a peak hold circuit 94, and E
The peak is held by a hold signal from the CU 3O, and A/D conversion is performed by an analog-to-digital (A/D) converter 95 at a timing of 306^TDC for each cylinder. The output value at that time is VA/D in the following equation.

A/D converted output +1lIVA/D is l1C118
0 is input. In the EC 1180, the average level Vm is obtained by averaging by performing a rounding calculation as shown in the following equation, for example.

Vmi=V+w(i-t)+[V A/D
-Vm (+-1>) /'v("11) where,
Vmi is the current calculation result, Vm (i-1) is the previous calculation result, and W is the rough coefficient.

Next, the energization advance control and the high voltage generator 110 will be explained based on FIG. 4. As shown, the oscillation circuit 11
1, inverter 112, AND gate 11
3, 114,) transistors 115, 116, diodes 117, 118, and a transformer 119. Here, the oscillation circuit 111 is composed of a known astable multi-pipe rake, and generates a square wave pulse of about l(lklLz).This square wave pulse is
is applied to the D gate 113 via the inverter 112,
On the other hand, it is added as is to the AND gate 114,
Pulses with opposite phases are applied to both AND gates 113 and 114. Also, the AND gates 113 and 114 receive the control signal of the EC1180, that is, the ignition signal (
Igt) is input. transistor 115,
116 is the NO gate 113°114 whose base is respectively
The emitter is grounded and the collector is connected to the transformer 119 via diodes 117 and 118, respectively. The transformer 119 has a primary coil 119a and a secondary coil 119 with a winding ratio of approximately 100.
The secondary coil 119C boosts the pulse voltage applied to the negative secondary coil 119a and outputs it from the secondary coil 119C.The intermediate terminal 119b is connected to the positive terminal of the power source 121. The secondary coil 119c is connected to a power distributor (not shown) and is connected to a spark plug 120. ECU3
When Lebel's Igt signal from O is applied, a high voltage is continuously generated, and a discharge occurs in the gap of the spark plug 120. Also, when a 0-level Igt signal from ECU 3O is applied, high voltage is no longer generated and the spark plug 12
0 gear gear stops discharging.

A first embodiment of the present invention will be described based on the flowchart of FIG. The program is executed by the 900CA interrupt. In step 201, starter switch 2
A signal STA from 0 is called in.

In step 202, it is determined whether STA is -1 or not.
If STA = 1, it is in the start state; if STA = 0, it is not in the start state), and if STA = 1, that is, in the start state, the process proceeds to step 210, where the Igt signal is set to the level and spark ignition is performed. If STA=O, that is, it is not in the start state, the process advances to step 203. In step 203, the exhaust temperature TE is read from the output of the exhaust temperature sensor 50. In step 204, it is determined whether the exhaust gas temperature has reached a certain temperature or higher (200° C. in this embodiment), that is, whether the engine is in a warm-up state. If it is not in the warm-up state, the process advances to step 210,
Set the GT signal to the level and ignite the spark. If it is in the warm-up state, the process advances to step 205.

In step 205, the water temperature Tw is determined from the output of the water temperature sensor 40.
Attract. In step 206, the water temperature is higher than a certain temperature (
In this embodiment, it is determined whether the temperature is 60° C., that is, the warm-up state. If the engine is not warmed up, the process proceeds to step 210, where the Igt signal is set to level and spark ignition is performed. If it is in the warm-up state, the process advances to step 207. That’s it, step 20
3 to step 206 is a flowchart in which a warm-up state is detected, and if the warm-up state is not present, spark ignition is executed. The warm-up state may be detected only by the water temperature in steps 205 and 206. As in this example, when the warm-up state is determined based on both exhaust temperature and water temperature, in the unlikely event that the water temperature does not reach the target level, due to an increase in warm-up amount or a delay in the ignition timing, only the exhaust temperature This has the advantage of eliminating the problem of misfires caused by stopping ignition-like discharge when the temperature is high. In step 207, as shown in FIG. 6, a spark ignition region predetermined by a map of engine speed Ne and load (intake air!/revolution) Q/Ne is called in. If it is outside the spark ignition region, Fl becomes a level, and if it is outside the spark ignition region, Fl becomes O level.

In step 208, it is determined whether Fl is 1 or not.
If l is not 1, that is, in the spark ignition region defined by the map in FIG. 6, the process proceeds to step 210, rgt is set to level, and spark ignition is performed. Further, if Fl is 1, it is determined that the spark ignition region is outside, and the process proceeds to step 209. tgt reaches the θ level, and spark ignition is stopped, that is, self-ignition is performed. The above steps 200 to 211 are not a start state but a warm-up state, and if it is outside the spark ignition range, it is regarded as a self-ignition state and spark ignition is stopped, and if it is not, spark ignition is performed. be.

The map shown in Figure 6 shows a region where the amount of intake air per revolution (Q/Ne), which represents the load, is relatively high and a region where the engine speed (Ne) is relatively low (idling region). ) is considered to be a spark ignition region where self-ignition is difficult.

Next, a second embodiment of the present invention will be described based on FIG. 7. Note that the same numbers are assigned to the same parts as in the first embodiment (FIG. 5), and explanations thereof will be omitted. Step 212 is the activation of a known ACC switch incorporated in the throttle valve opening sensor 60 (FIG. 1). The throttle valve opening sensor has a 〇〇 switch that detects the throttle opening speed, which is input to the ECU 80, and when the opening speed exceeds a certain level, it becomes ACCCC, and a transient state can be detected.

Step 213 determines whether ACC=1.

If ACC=1, that is, in a transient state, the process proceeds to step 210, where Igt is set to the level and spark ignition is performed.

If ACC=0, that is, in a steady state, the process proceeds to step 209, where Igt is set to the θ level and spark ignition is stopped.

Next, a third embodiment of the present invention will be described based on FIG. 8. Note that the same numbers are assigned to the same parts as in the first embodiment (FIG. 5), and explanations thereof will be omitted. Step 214 calls in the rotational fluctuation (in this embodiment, the rotational speed change for 2 seconds) ΔNe calculated from the output of the crank angle sensor 10. In step 215, the rotational fluctuation ΔNe is greater than or equal to a certain value (5 in this embodiment).
00 rpm). 500rp
If the rotational speed is greater than m, that is, if the rotational fluctuation is large, the process proceeds to step 210, where Igt is set to level and spark ignition is performed.

If the rotational fluctuation is small, the process advances to step 216. Step 216 is a variation (
ΔQ/Ne) (load change for 2 seconds in this embodiment). In step 217, if ΔQ/Ne>0.5, that is, if the load change is large, the process advances to step 210 and t
Set the GT to the rubel and ignite the spark. ΔQ/Ne>0.5
If not, it is assumed that the load fluctuation is small, that is, it is in a steady state, and the process proceeds to step 209, where Igt is set to 0 level and spark ignition is stopped.

Next, a fourth embodiment of the present invention will be described based on FIG. 9. Note that the same numbers are assigned to the parts common to the third embodiment (FIG. 8), and the description thereof will be omitted. In addition, Figure 9 is the same as ■ in Figure 8.
, ■ indicates the subsequent steps. In step 218, the signal from the combustion pressure sensor 90 (FIG. 1) is processed as shown in FIGS.
(see formula).

In step 219, the rotation speed Ne is set in advance as shown in FIG.
From the map of values given to the load Q/Ne, a value that meets the conditions is called in. Step 220 multiplies K and Vm to obtain -Vm as the determination level. Although the judgment level K/Vm is not shown in FIG. 9, an offset voltage Os for noise countermeasures is added, and the judgment level=K −Vm +
It may also be Os.

Step 211 is the A/D conversion value V of the combustion pressure sensor 90.
Load the A/D and proceed to step 222. Step 22
Step 2 compares the judgment level K.Vm and the A/D conversion value V A/D, and if V A/D becomes lower than the judgment level, that is, if the combustion pressure decreases from a certain constant state, the process proceeds to step 210. Turn the Igt into a rubel and ignite the spark. In addition,
In such cases, it is desirable to warn the driver using a warning buzzer or lamp. If the combustion pressure is above a certain level, it is assumed to be in a stable self-ignition state, step 20.
Proceed to step 9 and set Igt to 0 level so that no spark ignites. In this embodiment, the determination in step 222 is made only once, and it is determined whether to proceed to step 209 or step 210.
9 or step 210 may be included.

In addition, in the map shown in Fig. 10, 1 represents the load.
The map is such that the value increases as the amount of intake air per rotation (Q/Ne) is relatively low and as the engine speed is relatively high.

FIG. 11 is a sectional view of a two-stroke internal combustion engine to which the present invention can be applied. The various sensors shown in FIG. 1, namely the crank angle sensor 10, the starter switch (S/W
) 20 (not shown in FIG. 11), water temperature sensor 40. Exhaust temperature sensor 50, throttle opening sensor 60
, an air flow meter 70, and a combustion pressure sensor 90 are installed at appropriate positions on the two-stroke internal combustion engine as shown in FIG. Further, the microcomputer (ECU) 80S fuel injection control section 100, energization advance angle control and high voltage generator 110 shown in FIG. 1 are shown by block lines in FIG.

As for the structure of a two-stroke internal combustion engine, in FIG. 11, 1 is a crankcase, 2 is a cylinder block fixed on the crankcase 1, 3 is a cylinder head fixed on the cylinder block 2, and 4 is a cylinder block 2. 6 is a combustion chamber formed between the cylinder bore 3 and the piston 4, 7 is an ignition plug, 8 is a crank chamber formed in the crankcase 1, 9 is a balance weight , 11 is a connecting rod, 12 is an intake pipe, 18 is an exhaust port, 19 is a mechanical supercharger driven by the engine itself, 21 is an electromagnetic clutch, and 23 is an air cleaner.

An air flow meter 70 provided immediately downstream of the air cleaner 23 measures the total amount of air taken into the engine body. The downstream side of the air flow meter 70 is divided into a first intake system A that supplies fresh air in the entire operating range of the engine, and a second intake system B that supplies only air in the operating range above a predetermined load.

The first intake system A includes a first throttle valve 2 that is linked to the accelerator pedal 27 and controls the air flow rate throughout the entire operating range of the engine.
6 is provided. The flow-controlled air passes through the intake passage 13 and the reversal valve 28 consisting of a reed valve, the intake port opening on the inner wall surface of the cylinder 5, the gap 29 between the piston 4 and the cylinder wall surface, and the back side of the piston 4 to the crank chamber. 8 is inhaled.

In addition to air, lubricating oil for lubricating the crankshaft, pistons, etc. is also sucked into the crank chamber 8. The air that has been primarily compressed (supercharged) in the crank chamber 8 is pulsated together with the lubricating oil mist into a relatively elongated scavenging passage section (first scavenging passage) 30 from a fresh air flow 31 that opens at the bottom of the crank chamber 8. It flows in as a stream. This scavenging passage portion 30 extends outside the crank chamber 8 in an arc shape. A first fuel injector 25a that injects light oil is disposed in the middle of the scavenging passage portion 30, and a second fuel injector 25b that injects gasoline is disposed downstream thereof. First fuel injector 25
a injects light oil in the light to medium load range up to a predetermined load;
The second fuel injector 25b injects gasoline in a high output range above a predetermined load or in a starting/warming-up state. The downstream side of the elongated scavenging passage section 30 is divided into two parts, forming a scavenging passage section with a large cross-sectional area.The air-fuel mixture flows into this section and is decelerated. The first scavenging boat 32, which is open to the front, flows into the cylinder combustion chamber 6 at a low speed. Therefore, in the operating range up to a predetermined load, a stratified state is maintained between the high-temperature exhaust gas remaining in the cylinder combustion chamber 6 and the gas oil mixture that has flowed in, and the compression stroke continues, resulting in adiabatic compression. As a result, the fuel is heated by the high-temperature atmosphere, and the air-fuel mixture self-ignites without the use of the ignition plug 7.

The second intake system B is connected to the second scavenging passage 41, and the second
The scavenging passage 41 has a second throttle valve 42 that opens in conjunction with the accelerator pedal 27 at least in the operating range above a predetermined load.
is provided. A mechanical supercharger 19 is provided downstream of the mechanical supercharger 19, and further downstream of the mechanical supercharger 19, a second scavenging boat 44 which is branched into two branches is directly operated via a second check valve 43 which is provided for each cylinder. It opens at a position relatively close to the exhaust port 18 on the inner wall surface of the cylinder 5. Therefore, in an operating range where the engine load is higher than a predetermined load, the electromagnetic clutch 21 of the mechanical supercharger 19 is turned on, the pump of the supercharger 19 is driven, and scavenging air is supercharged. Therefore, the supercharged air whose flow rate is controlled by the second throttle valve 42 flows directly from the second scavenging passage 41 into the combustion chamber 6 at a high speed via the check valve 43, and remains in the combustion chamber 6. To quickly scavenge exhaust gas from an exhaust port 18. After that, the air-fuel mixture from the first intake system A, that is, the intake passage 13, the crank chamber 8, and the elongated scavenging passage 30.
An air-fuel mixture in which fuel (gasoline) injected from the second fuel injector 25b is mixed with the air that has passed through the first scavenging boat 32 flows into the combustion chamber 6 at a low speed. 1st
A part of the air flowing in from the scavenging boat 32 is sent to the exhaust port 1.
However, the air-fuel mixture flowing in from the first scavenging boat 32 flows into a position far from the exhaust port 18 of the combustion chamber 6 when the remaining exhaust gas is finished being scavenged by the supercharged air flowing in from the second scavenging boat 44. Therefore, the air-fuel mixture is prevented from blowing through to the exhaust port 18. In addition, in the operating range above a predetermined load, the amount of fuel (gasoline) injected from the fuel injector 25b needs to be enriched by the amount of air flowing in from the second scavenging port 44, but even with such a rich mixture, there is a long and narrow While passing through the scavenging road section 30, the gas is sufficiently vaporized, and after flowing into the combustion chamber 6, it is ignited and burned by the spark plug 7.

〔Effect of the invention〕

According to the present invention, it is possible to stop the discharge of the spark plug in the self-ignition region during light and medium loads that are operated for a long time, such as in a two-stroke internal combustion engine for automobiles. consumption can be significantly reduced. Additionally, high energy discharge can be used in operating ranges where self-ignition is difficult. Additionally, the area considered to be the self-ignition area does not necessarily match the actual self-ignition area, but if this ``regarded area'' is set to sufficiently cover the actual self-ignition area, misfires and engine stoppages can occur. No problem arises.

[Brief explanation of drawings]

Fig. 1 is a block diagram showing the ignition control unit of the two-stroke internal combustion engine of the present invention, Fig. 2 is a block diagram showing the configuration for combustion pressure detection, Fig. 3 is a timing chart for combustion pressure detection, and Fig. 4 5 is a control flowchart of the first embodiment of the present invention, FIG. 6 is a map showing the spark ignition region, and FIG. 7 is a diagram showing the configuration of the energization advance control and the high voltage generator. 8 is a control flowchart of the third embodiment of the present invention, FIG. 9 is a control flowchart of the fourth embodiment of the present invention, and FIG. 10 is a control flowchart of the fourth embodiment of the present invention.
FIG. 1I, a value map used in the embodiment, is a sectional view of a two-stroke internal combustion engine to which the present invention can be applied. lO...Crank angle sensor, 20...Starter switch (S/W), 40...
Water temperature sensor, 50... Exhaust temperature sensor, 60... Throttle opening sensor, 70... Air flow meter, 80... Microcomputer (ECU>, 90...
... Combustion pressure sensor 100 ... Fuel injection control section, 110 ... Current supply advance control and high voltage generator.

Claims (1)

[Scope of Claims] 1. In a two-stroke internal combustion engine that has a self-ignition operating range where ignition can be ignited without spark plug discharge, and an operating range where self-ignition is difficult such as during startup, warm-up, and high load. An ignition control device for a two-stroke internal combustion engine that, when it detects that the engine temperature is above a specific temperature and below a predetermined load, is considered to be in a completely self-ignition operating range and stops discharging the spark plug. 2. A predetermined map is stored in advance that defines the spark ignition area as a region where the load is relatively high, and the spark plug stops discharging when it is detected that it is not in the spark ignition area. An ignition control device according to claim 1, wherein the ignition control device is configured to: 3. Ignition control according to claim 2, which discharges the spark plug regardless of the area of the map when any one of engine speed, intake air amount, and throttle opening changes by a predetermined value or more. Device. 4. The ignition control device according to claim 2, which discharges the spark plug regardless of the area of the map when the combustion pressure of the engine decreases from a certain constant state.