JPS62223469A - Ignition device for internal combustion engine - Google Patents

Abstract

PURPOSE:To make it possible to prevent a spark plug from smoking with a simple circuit arrangement, by enabling electric discharge for purifying the spark plug at the termination of each intake stroke of an engine during cold operation or the like. CONSTITUTION:A microprocessor 11 delivers a control signal iGt1 with ignition timing during engine starting, hot partial load operation or high load operation, and a purifying electric discharge control signal iGt2 at the termination of each suction stroke during cold operation in accordance with several sensors 7 through 10 for intake-air pressure, rotating angle, water temperature and a starter. These control signals are distributed for distributed signals (a, b; c, d) for first and forth engine cylinders, and second and third engine cylinders through distributing circuits 13, 14, and are then delivered to an ignitor 2 through OR circuits 15, 16 to allow spark plugs 41-44 to perform electrical discharge for firing or purification. Thus, it is possible to prevent the spark plug from smoking without causing the high load characteristic and drivability of the engine during cold operation of the engine to deteriorate. Further, it is not necessary to provide an ignition coil or the like for every spark plug, thereby it is possible to simplify the circuit arrangement.

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, in a distributor-less ignition (DLI) in which a distributor is removed, by performing spark plug cleaning discharge at the end of the intake stroke. The present invention relates to a DL1 ignition system for an internal combustion engine that takes measures against spark plug smoldering without causing deterioration of characteristics under high load due to changes in the heat value of the spark plug or deterioration of drivability at low temperatures due to lean conditions.

[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. Pre-ignition is likely to occur when the temperature of the spark plug rises under high load, and misfire occurs due to excessive fR at low temperatures. This occurs because carbon adheres to the spark plug due to the combustion of the E1 gas, and ignition energy leaks through the carbon. 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. Plug crumbling is a problem.

Conventionally, in order to prevent this spark plug from smoldering,
Although it has the disadvantage 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 carbon attached to the spark plug with a long electric discharge (for example, JP-A-57- 68562). In the latter method, the discharge start timing (so-called ignition time M
) is advanced to around 40"CA before top dead center to lengthen the discharge duration and burn off the carbon with the thermal energy of the discharge energy. In this case, about 25 m5ec is required as a discharge time at the time of starting.

On the other hand, if the ignition timing is advanced using the method described above,
Conversely, 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 varies greatly, leading to torque fluctuations and engine speed fluctuations, which has the disadvantage of deteriorating drivability. Additionally, experiments have shown that unnecessary long-term discharge in an ignitable atmosphere tends to generate carbon near the spark plug, and this carbon is pushed into the bore of the spark plug along with the upper limit of the bis-bond, forming an insulator. It was found that the deposition in the areas further progressed. Furthermore, there is also the problem that the power consumed for extremely long discharge increases, resulting in a significant progress in battery consumption.

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 problems] The present invention is a DLI ignition system for an internal combustion engine that solves the above-mentioned problems, and includes a rotation angle sensor, an intake pressure sensor, and a water temperature sensor that detect each operating state of the engine. , a starter, and the detection signals from these generate a control signal for ignition discharge (ignition signal) and a control signal for clean discharge (clean signal) according to each operating state.
A microprocessor as an electronic control means that calculates and outputs a The ignition signal is composed of an igniter with a built-in power transistor that switches the primary current of the ignition coil in order to generate a true current in the ignition plug, and the ignition signal and the clean signal obtained by each distribution circuit are OR-combined before inputting to the igniter. However, during starting, warm partial load, and warm high load, the igniter is operated only at the ignition timing (M at the end of the compression stroke), and when cold, the ignition discharge is performed at the ignition timing with a TH clean discharge at the end of the intake stroke. It is characterized by the fact that

〔Example〕

FIG. 1 is a block diagram of an embodiment of an ignition device for an internal combustion engine according to the present invention. This embodiment is a case of a four-cylinder engine, and in FIG. 1, 1 is an engine control computer (ECU) for electronically controlling the engine.
, a microprocessor 11, a waveform shaping circuit 12,
It is composed of distribution circuits 13 and 14 and OR circuits 15 and 16. Rotation angle sensor 8 installed on the engine
Detection number 43 is sent to the microprocessor 11 via the waveform shaping circuit 12, and also to the intake pressure sensor 7, water temperature sensor 9,
Detection signals from the starter 10 are respectively input to the microprocessor 11 via a Δ/D converter (not shown). Note that G, , G2 are signals after waveform shaping of the generated voltage, and NE is a signal of the rotational speed.

The microprocessor 11 first determines whether it is starting, cold time, or warm time based on the detection signals from the water temperature sensor 9 and the starter sensor 10, based on a predetermined map, and then determines whether it is starting time, cold time, or warm time based on the detection signals from the water temperature sensor 9 and the starter sensor 10. 8 etc., it is determined whether the load is light or high, and based on these data, the timing of ignition discharge and the timing of clean discharge are calculated, and the control signal for ignition discharge (iGt+) and the control signal for clean discharge ( iGtz). This control flow is shown in detail in FIG. 3, which will be described later. Next, these control signals iGt and 1Gt2 are input to distribution circuits 13 and 14, and iGt is N[11, distribution signal a for the affected four cylinders.
1Gt
Similarly, 2 is the distribution signal C for Hiro 1, Hiro 4, Floor 2, and Floor 3.
It is divided into 1d. These signals a, c, b and d are input to OR circuits 15 and 16. OR circuit 1
5, a which is iGt for the Nb, I, and Na4 groups and C which is 1Gt2 are OR-combined, and the power transistor 23 is driven through the processing circuit 21 of the igniter 2, and the one-blow type flow of the ignition coil 31 is e is switched to generate a high voltage in the secondary coil, and discharge for cleaning and ignition is performed in the spark plug 4I of the Th1 cylinder and the spark plug 44 of the 1lh4 cylinder.

On the other hand, in the OR circuit 16, 1Gtl for the floor 2 and floor 3 cylinders is
and 1Gt2 are coupled to drive the power transistor 24 through the processing circuit 22 of the igniter 2, and the ignition coil 3
2 through Hiro 2 cylinder and Hiro 3 cylinder spark plug 42, 4
3, both the cleaning discharge and the ignition discharge are repeated alternately.

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

In FIG. 2, as described above (iGt is a control signal for ignition discharge, 1Gt2 is a control signal for clean discharge, a and b are distribution signals of iGt, C and d are distribution signals of 1Gt2, A is the output of the OR circuit 15, B is the output of the OR circuit 16, and e and f are the primary current waveforms of the coils 31 and 32.

Note that TDC is the top dead center of each cylinder. Further, the numbers in each signal indicate the respective cylinder numbers, and the pulses with diagonal lines indicate cleaning discharge. As mentioned above (, signal A is the OR of a and C
The signal B is an OR waveform of b and d. - As is clear from the waveforms of blow mold flows e and f, both ignition and cleaning discharges are performed alternately in both ignition coils 31 and 32. That is, as is clear from the figure, the timing of the ignition discharge is set at the end of the compression stroke of the cylinder to be combusted, at a time that is comprehensively suited from the viewpoint of output, fuel consumption, exhaust emissions, etc. On the other hand, the clean discharge is performed at the end of the suction stroke, and in this embodiment, the calculation time is shortened by performing it 150° CA before the timing of the ignition discharge. Since this device is used in a DLI ignition system, discharge is also performed at the end of the exhaust stroke and the end of the expansion stroke other than the above-mentioned discharge, but since combustion has finished in both cases, there is no negative effect on actual combustion.

FIG. 3 is a control flowchart of the ignition device according to the present invention. This routine is an interrupt routine, and first it is determined whether the starter switch 10 is on or not (step 1).
, when it is on, the cleaning discharge is not performed and the ignition discharge is 1Gtl.
(Steps 5 and 6). When the starter switch 10 is off, the hot water sensor 9 determines whether the engine cooling water temperature is 25°C or higher (Step 2), and if the temperature is 10°C or higher, the cleaning discharge is not performed and the ignition discharge is started (Step 5). , 6). Cleaning discharge 1 when the water temperature is below 25℃
Timing calculation of GL2 is performed (step 3), and the result is output to the igniter via the distribution circuit/OR circuit (step 4).

〔Effect of the invention〕

According to the present invention, in a DLI ignition device for an internal combustion engine,
By controlling the spark plug cleaning discharge to occur at the end of the intake stroke when the engine is cold, it is possible to prevent the spark plug from smoldering without deteriorating the characteristics at high loads or drivability at low temperatures. In addition, since the above control is performed by ORing the ignition signal and the Ylfflff heavy discharge signal before inputting the igniter, there is no need to provide an ignition coil, power transistor, and ECU for each spark plug, and the high voltage for preventing backflow is eliminated. Since no diode is required, costs can be significantly reduced.

On the other hand, since ignition and cleaning are simultaneously performed in the coil, there is no need to connect high-voltage cords in parallel in a Y-shape, which greatly improves reliability and reduces radio wave interference.

[Brief explanation of drawings]

FIG. 1 is a block diagram of an embodiment of the ignition system for an internal combustion engine according to the present invention, FIG. 2 is a signal timing chart of the system shown in FIG. 1, and FIG. 3 is a control flowchart of the system shown in FIG. (Explanation of symbols) 1...Engine control computer, 2.
...Igniter, 7.Intake pressure sensor, 8.
...Rotation angle sensor, 9...Water temperature sensor, 10.
...Starter, 11...Microprocessor, 12...Waveform shaping circuit, 13, 14...Distribution circuit, 15, 16...OR circuit, 21, 22
...processing circuit, 31, 32...ignition coil, 4
1-44...Spark plug. Figure 1 Signal timing chart of the device Figure 2

Claims (1)

[Claims] 1. In the ignition system of an internal combustion engine, a rotation angle sensor, an intake pressure sensor, and a water temperature sensor detect each operating state of the engine.
Based on the detection signal of the starter sensor, control is performed to first perform a cleaning discharge at the end of the suction stroke during cold operation, followed by an ignition discharge at the end of the compression stroke. electronic control means for outputting ignition and cleaning discharge control signals for controlling the ignition discharge only at the end of the compression stroke during high load; and distributing the ignition and cleaning control signals to predetermined cylinders. an OR circuit for ORing the outputs of the distribution means; and an igniter for switching the primary current of the ignition coil to generate high voltage in the spark plug based on the output of the OR circuit. An ignition system for an internal combustion engine characterized by: