JPS62165577A - Ignition device for internal combustion engine - Google Patents

Abstract

PURPOSE:To enhance the drivability of an engine, by providing an ignition coil and a purifying coil in parallel with each other, by controlling them differ ently in accordance with load conditions of the engine during starting operation, cold engine operation and hot engine operation. CONSTITUTION:An ignition igniter 21 and an igniter 22 for purifying a spark plug 4 are provided in a stage after an ECU 1 which receives detection signals from a rotating angle sensor 8, a water temperature sensor 9 and an intake-air pressure sensor 11 and calculates an ignition timing and a purifying electric discharge timing. Further, during starting operation the igniter 21 allows first ignition coils 33, 33 alone to electrically discharge at the termination of a com pression stroke, but during cold engine operation, the igniter 22 allows second ignition coil 33, 34 alone to electrically discharge at the termination of a suction stroke. Meanwhile all coils 31-34 are allowed to electrically discharged at the termination of a compression stroke. Further, during low load operation all coils 31-34 are electrically discharged, but during high load operation the first ignition coils 31, 33 are alone discharged.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to an ignition system for an internal combustion engine, and in particular, to ensure the ignition performance of the ignition system in a partial load region, and to improve characteristics under high load and drivability at low temperatures. Use an ignition system for internal combustion engines that takes measures to prevent spark plug smoldering and suppresses electrode wear.

[Prior Art and Problems to be Solved by the Invention] Conventionally, as a countermeasure against pre-ignition or misfire in an internal combustion engine, a method has been used to appropriately adjust the heat value of a spark plug. Preignition tends to occur when the temperature of the spark plug rises under high load, and misfire occurs when carbon adheres to the spark plug due to combustion of a rich mixture at low temperatures, and ignition energy leaks through the carbon. occurs because of Therefore, these countermeasures are taken by adjusting the heat value mentioned above, but if too much emphasis is placed on the heat value of the spark plug at high loads to avoid engine damage due to pre-ignition, it may actually cause ignition at low temperatures. Smoldering plugs are a problem.

Conventionally, in order to prevent this spark plug from smoldering,
Although there is a problem of deteriorating drivability at low temperatures, there are methods to thin the air-fuel mixture to suppress the amount of carbon generated, and methods to burn off the carbon attached to the spark plugs with a long electric discharge (for example, 1986-68562). In the latter method, only the start timing of the discharge (so-called ignition timing) is advanced to around 40° CA before top dead center, the duration of the discharge is lengthened, and the carbon is burned off by the thermal energy of the discharge energy. In this case, approximately 25m5ec is required as a discharge time at startup.

On the other hand, when the ignition timing is advanced, the misfire rate increases as the ignition timing is advanced. Therefore, if the discharge duration is increased, the timing at which the air-fuel mixture is ignited will vary greatly, leading to torque fluctuations and engine rotational speed fluctuations, resulting in a problem of deterioration of drivability. Additionally, experiments have shown that unnecessary long-term discharge in an ignitable atmosphere tends to generate carbon near the spark plug, and as the piston rises, this carbon is pushed into the pocket of the spark plug and deposited on the insulator. It was found that the process progressed further.

Furthermore, there is also the problem that the power consumed for a very long discharge increases, so that the battery wears out significantly.

Furthermore, in conventional internal combustion engines, the ignitability of the ignition system becomes a problem because the mixture is made lean or a large amount of "exhaust gas recirculation" is performed under partial load in order to improve fuel efficiency. As a countermeasure for this, it is necessary to improve the spark energy (in particular, increase the discharge current), but increasing the spark energy will cause significant wear on the spark plug electrodes, and will also increase the spark energy. The heat generated by the igniter's power transistor also poses a problem.

[Means and effects for solving the problem] An electronic control circuit (ECU) that inputs signals from a rotation angle sensor, an intake pressure sensor, a water temperature sensor, and a starter switch and calculates the ignition timing and clean discharge timing; A first igniter that distributes the primary current to the first ignition coil, a second igniter that distributes the primary current to the second ignition coil, and high voltage sides of the first ignition coil and the second ignition coil. wired O
Equipped with R-connected high-pressure cord and spark plugs for each cylinder,
When starting, only the first ignition coil is discharged at the end of the compression stroke, when cold, only the second ignition coil is first discharged at the end of the suction stroke, and then the first and second ignition coils are simultaneously discharged at the end of the compression stroke. During warm and light loads, the first and second ignition coils are simultaneously discharged only at the end of the compression stroke, and during warm and high loads, only the first ignition coil is discharged at the end of the compression stroke, thereby cleaning the spark plug. and ignition, and further according to the present invention, the first coil and the second coil are connected to a coil having a common function.
The present invention is characterized in that the primary side current of the common coil is switched by the first and second igniters to perform cleaning and ignition.

〔Example〕

FIG. 1 is a circuit diagram of an embodiment of an ignition device for an internal combustion engine according to the present invention. In FIG. 1, 1 is an engine control computer (E) for electronically controlling the engine.
CU), the engine speed detected by the rotation angle sensor 8, the engine cooling water temperature detected by the water temperature sensor 9, the engine starting signal from the starter 10, and the intake air detected by the intake pressure sensor 11. Each tube pressure is taken in as an input signal, a clean discharge timing and an ignition discharge timing suitable for the operating conditions are calculated from these, and control signals iGL+, iGh are output to the first igniter 21 and second igniter 22 in the subsequent stage. , an ignition activation signal fGf produced by the collector voltage of the power transistor that switches the primary current of the ignition coils 31 and 33 is returned from the first igniter 21.

The igniter control circuit 2 is composed of a first and a second igniter control circuit, and switches the primary side current of the ignition coils 31 to 34 in the subsequent stage based on a signal from the ECU 1. 21 is for ignition, and 22 is for cleaning. In the case of a 4-cylinder engine, the ignition coil should be <31 to 3 as shown in the diagram.
Four ignition coils are provided, 31 and 33 serving as a first ignition coil to carry the ignition discharge, and 32 and 34 serving as second ignition coils to carry the spark plug cleaning discharge.

Note that 313 to 34a are diodes for blocking backflow.

4 is a spark plug for each cylinder, and as shown in the figure, coils 31 and 32 are connected in parallel for the affected 1st cylinder and the 4th cylinder to operate as a wire FOR, and the spark plugs for the 1st cylinder and the 3rd cylinder are connected in parallel. On the other hand, coils 33 and 34 are connected in parallel and similarly operate as a wired OR.

In such a configuration, the control of the present invention performs cleaning discharge and ignition discharge at the timing of starting, cold and warm periods at the end of the compression stroke and at the end of the suction stroke at the timings detailed below.

FIG. 2 is a signal timing chart of the device shown in FIG.

In Fig. 2, first, as shown in (C), at the time of starting, the starter IO detects the starting state, and during high load during warm conditions, the water temperature sensor 9 detects that the cooling water temperature is 30°C or higher. The intake pressure sensor 11 detects that the intake pipe pressure is a high load of 1150 mdg or more, and based on these operating conditions, command signals 1Gt1 shown in EcU 1 to g and command signals jGtz shown in h are sent to the first igniter. 21 and a second igniter 22.

In this case, as shown in h, <1Gtz (h) remains at a low level, so the second igniter 22 does not operate, and only the first igniter 21 ignites at the ignition timing at the end of the compression stroke, causing a clean No discharge occurs. i is 2
This is the current waveform of the next coil, and the spark energy at this time is 4
It is 0mj. However, at high loads, the mixture is rich, so 30
Energy equal to or greater than mj is sufficient. This makes it possible to suppress electrode wear under conditions of high heat load. This is because electrode wear is proportional to the electrode temperature and spark energy.

Next, the warm light load condition will be explained. As shown in (B), when the load is warm and light, the water temperature sensor 9 indicates that the cooling water temperature is 3.
E
As shown in d and e at the same output timing from CU l
Output tGt+(dl, i G t z (a) to the first igniter 21 and the second igniter 22. iGt
+fdl and 1Gtz(e) cause the first ignition coil and second ignition coil to operate simultaneously only at the end of the compression stroke, so the spark energy is 8Q+wj, which is the sum of these as shown in the waveform at f, and the air-fuel mixture is lean. This can improve ignitability and prevent misfires.

Furthermore, the cold time will be explained. As shown in (A),
The water temperature sensor 9 detects that the cooling water temperature is less than 30°C, and the command signal iG is used to discharge only at the end of the compression stroke.
t, fa) to the first igniter 21 twice at the end of the suction stroke and at the end of the compression stroke.
is input to the second igniter from the ECU 1, and the first ignition coil and the second ignition coil operate, so at the end of the intake stroke, the spark energy is discharged at <40 mj as shown in C, and the spark plug 4 is The adhering carbon is oxidized and cleaned, and then, at the ignition timing at the end of the compression stroke, an ignition discharge is performed with a spark energy of <80 mj as shown in C. This makes it possible to prevent poor starting and deterioration of drivability when the engine is cold due to smoldering of the spark plug, and because the spark energy is large, it is possible to make the air-fuel mixture leaner when the engine is cold, thereby improving fuel efficiency.

FIG. 3 is another embodiment of the signal timing chart shown in FIG. 2. At low speed and light load in warm conditions, the waveform shown in (A) is the same as that in FIG. 2 (B). When the load is warm at high speed and under light load, it changes as shown in (B). That is, the water temperature sensor 9 detects that the cooling water temperature is 30°C or higher, and the intake pressure sensor 11 detects that the intake pipe pressure is 1150 mmH.
When the rotation angle sensor 8 detects a light load of less than 300 rpm, and the rotation angle sensor 8 detects a low speed range of less than 300 rpm, the first and second igniters 21 and 22 are activated, as in the embodiment shown in FIG. Because they operate simultaneously, Figure 3 (
A) and f in FIG. 2(B), the spark current at the ignition plug 4 is doubled (80 mj) and the spark duration remains unchanged. On the other hand, in the high speed range of 3000 rpm or more, Figure 3 (B
), the spark duration can be lengthened by delaying the timing of 1Gtz of the second igniter 22 by about 1 m5ec from the timing of 1G12 of the first igniter 21. This makes it possible to prevent misfires caused by the arc blowing out under conditions of strong turbulence in the combustion chamber at high speeds and light loads. In this case, for example, the spark current of the first ignition coil and the second ignition coil are both 40 mA, and the spark duration is both 1.5
Since it is m5ec, the spark duration at high speed and light load is 2
．． It will be 6m5ec.

In this example, it is possible to oxidize and clean the carbon that has adhered to the spark plug by discharging in an oxidizing atmosphere at the end of the intake stroke, and the spark energy can be increased in cold and warm conditions, resulting in drivability. As well as improving fuel efficiency, it becomes possible to make the air-fuel mixture leaner or to recirculate a large amount of exhaust gas, improving fuel efficiency. In addition, the spark energy during high loads can be reduced, making it possible to avoid high-energy discharge under conditions where the spark plug electrode temperature is high, preventing increased electrode wear, and further improving individual igniter and ignition Since the heat load on the coil can be suppressed to a small level, it is possible to improve the reliability of the igniter and the ignition coil.

FIG. 4 is a circuit diagram of another embodiment of the ignition system for an internal combustion engine according to the present invention. The difference from the embodiment shown in FIG. 1 is that one coil serves both for cleaning the ignition coil and for igniting.

That is, as in the embodiment shown in FIG.
Input the starting signal from , calculate the ignition timing and clean discharge timing according to each operating condition from these, and use the signal (iGdA
1GdB+, 1GdAz, and 1GdB) are output to the first igniter 21 and second igniter 22 provided at the subsequent stage. These igniters 21 and 22 are E
The primary currents of the ignition coils 31 and 32 are switched based on control signals a and b from the CU I, and spark discharge is generated in the spark plugs 41 to 44 via the high voltage cords 71 to 74.

FIG. 5 is a signal timing chart of the device shown in FIG.

In FIG. 5, (A) is a signal timing chart in a cold state, and (B) is a signal timing chart in a starting time and a warm state. Cooling water temperature is 3
When the temperature is cold below 0°C, the second igniter 22 is activated during the intake stroke by the output 1Gtz of IECtll, and the first igniter 21 is activated during the compression stroke by iGt, so the primary current of the ignition coil 31 is a. As shown in the waveform, as shown in C, after a clean discharge is performed at the end of the suction stroke, a discharge for ignition is performed at the ignition timing at the end of the compression stroke. ignition coil 3
In 2, the distribution is the signal (iGdA+ , tGd81 , , +
GdAz, 1GdBz) by ignition coils 31 and 1
A similar discharge occurs with a phase of 80°.

As shown in (B), at startup and during warm (cooling water temperature 30℃)
(above), since the discharge control signal 1Gt2 from the ECU 1 is not output and falls to a low level, the second igniter 22 does not operate at all, and only the first igniter 21 with 1Gtl fires the ignition coils 31, 32. The primary current becomes a', and as a result, discharge occurs only at the ignition timing at the end of the compression stroke, as shown by C'.

In this example, the cleaning ignition coil and the ignition ignition coil are made common, which makes it easier to install in the engine, reduces weight, and eliminates the need for wired OR connection of the secondary high voltage cord. This has the effect of reducing costs, improving reliability, shortening high-voltage cords, and reducing radio noise. Furthermore, significant cost reductions can be achieved by reducing the number of ignition coils, reducing the number of ignition coil mounting stays, and eliminating the high-voltage diode in the ignition coil.

〔Effect of the invention〕

According to the ignition system for an internal combustion engine according to the present invention, the ignition performance of the ignition system in the partial load region is ensured, and the smoldering of the plug and the ignition of the electrode are prevented without causing deterioration of high load characteristics or deterioration of drivability at low temperatures. It is possible to prevent wear and tear.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram of an embodiment of the ignition device according to the present invention, FIG. 2 is an example of a signal timing chart of the device in FIG. 1, FIG. 3 is another example of a signal timing chart of the device in FIG. 1, and FIG. FIG. 4 is a circuit diagram of another embodiment of the ignition device according to the present invention, and FIG. 5 is a signal timing chart of the device shown in FIG. (Explanation of symbols) l...Engine control computer, 2.
21.22...Igniter, 3.31-34...Ignition coil, 4...Spark plug, 7...High pressure cord, 8...Rotation angle sensor, 9...Water temperature sensor, 10. ...Start inch, 11...Intake pressure sensor. No, 4 No, l
No. 4 Figure 1: m signal timing chart of the device No. 4 No. I
No. 4 Fig. 1 Other example of signal timing chart of the device Fig. 3

Claims (1)

[Claims] 1. In an ignition system for an internal combustion engine, a first ignition coil for igniting an air-fuel mixture and a second ignition coil for cleaning a spark plug are provided in parallel, and at the time of starting, Only the first ignition coil is discharged at the end of the compression stroke, and when cold, only the second ignition coil is first discharged at the end of the suction stroke, and then the first and second ignition coils are discharged. At the same time, the first and second ignition coils are discharged at the end of the compression stroke during warm and light loads, and the first and second ignition coils are discharged at the end of the compression stroke during warm and high loads. An ignition device for an internal combustion engine, characterized in that only a coil is discharged at the end of a compression stroke. 2. In an ignition system for an internal combustion engine, first and second igniters are provided to control the ignition discharge and cleaning discharge of the ignition coil, and at the time of starting, only the first igniter is operated at the ignition timing, and the cooling When the engine is running at low load, only the second igniter is activated at the end of the suction stroke, and then the first and second igniters are activated at the same time at the ignition timing. An ignition system for an internal combustion engine, characterized in that the first and second igniters are operated simultaneously at the ignition timing, and only the first igniter is operated at the ignition timing during warm and high load conditions.