JPH02207180A - Multiple ignition controlling method upon starting - Google Patents

Abstract

PURPOSE:To improve the startability when an engine is cold by performing the ignition processing several times before and after the upper dead point every time each cylinder of the engine reaches the upper dead point only when the shark ignition engine is started. CONSTITUTION:A set transfer switch 5 is provided on an output circuit 1, a reference signal is outputted only to a one-shot circuit B by the function of a diode 6 when the switch 5 is turned off (during ordinary operation), and it is outputted to one-shot circuits B-D when the switch 5 is turned off (at the time of starting). The one-shot circuit B is triggered by the reference signal with the phi prior to the upper dead point at the time of starting, and an excitation start signal is outputted after the preset number of crank angle signals are counted. A one-shot circuit A1 is triggered by the excitation start signal, the preset number of crank angle signals corresponding to the dwell angle are counted, and an ignition signal is outputted. One-shot circuits A2 and A3 are then triggered in sequence, and ignition signals are outputted.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Field of Application) The present invention relates to a multiple ignition control method at startup that is employed in a spark ignition engine such as a gasoline engine.

(Prior Art) In spark ignition engines, electronic control is progressing to optimally control ignition timing according to operating conditions. The control method receives a reference signal indicating a specific crank position before top dead center (TDC) and a crank angle signal (pulses generated in units of 1° or 2°), and then responds to the operating conditions at that time. The ignition timing and dwell angle are determined, and the current to the ignition coil is turned on and off using a switching transistor.

Here, the time during which current is applied to the ignition coil expressed in crank angle is called the dwell angle, and this dwell angle becomes smaller at low speed rotation.

Since the ignition timing affects the output generated by each cylinder, the ignition timing is advanced as much as possible within the range where knocking does not occur during steady state to achieve a complete explosion.

On the other hand, it is known that the first explosion when the engine is cold is more likely to occur if the engine is shifted after top dead center. In addition,
FIGS. 6(a) and 6(b) show characteristic diagrams showing the ease with which initial explosion and complete explosion occur in a spark ignition engine.

Here, the T line indicates the cylinder gas temperature characteristics.

Spark ignition engines operate based on these characteristics, but the ignition control method adopted here is based on operating conditions such as engine speed, load, amount of change in load, cooling water temperature, etc. during steady operation. The ignition timing is controlled by performing ignition with an advance value that is a correction of the reference advance value, and using a fixed advance value during a transient period when the amount of change in load exceeds a certain value.

(Problem to be Solved by the Invention) By the way, in such a conventional ignition timing control method, ignition processing is performed once near the top dead center of each cylinder to achieve complete explosion. However, when starting the engine, especially when starting cold, it tends to take a long time for the first explosion to occur, and even if the first explosion occurs, it may not be followed by a complete explosion or the first explosions of other cylinders. However, starting performance may be poor.

In this way, it is desired to improve the deterioration in startability of spark ignition engines when they are cold.

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for controlling multiple ignitions at startup, which can improve the startability of a spark ignition engine.

(Means for Solving the Problems) The present invention is a method for determining the ignition timing according to the operating conditions of a spark ignition engine and igniting the engine, in which each cylinder of one engine is activated only when the spark ignition engine is started. It is characterized in that each time the dead center is reached, ignition processing is performed multiple times before and after each top dead center.

(Function) When a spark ignition engine is started, multiple ignition processes are performed, but the ignition process after top dead center promotes the occurrence of the first explosion, and once the first explosion is achieved. , another ignition treatment before top dead center can facilitate repeated detonations.

(Embodiment) FIGS. 3 to 5 show flowcharts of a CPU (computer) used in a multiple ignition control method at startup as an embodiment of the present invention.

This CPU enters control in the main routine by turning on the key of the main switch.

Here, initial function settings such as checking each function and setting initial values are performed, and then various operating information of the engine is read.6Then, the dwell angle for each ignition process is calculated based on the engine speed. .

After this, it is determined whether or not the engine speed calculated in the first interrupt routine described below is greater than the judgment speed. If the start is completed, the process goes to YES, and if the start is not completed, the process goes to NO.

When step a7 of YES is reached, the normally closed set changeover switch 5 shown in FIG. 1 is kept off, and a well-known ignition timing calculation is performed. The set changeover switch 5 (see Figure 1) is turned on when adopting a starting pattern in which ignition processing is performed three times before and after top dead center each time the reference signal for each cylinder is taken in, and once the reference signal for each cylinder is taken in. This is turned off when a steady pattern is entered into the ignition process.

In the ignition timing calculation routine of step a8, a well-known method is adopted in which the reference ignition timing is corrected and determined based on engine water temperature, engine speed, load, etc., and the target ignition timing φt is determined.

On the other hand, when step a6 is reached, the set changeover switch 5 is turned on, and a starting pattern is entered in which ignition processing is performed three times before and after the top dead center. Then, the target ignition timing is set to a fixed value ψ1 (here, 5 degrees before top dead center). Furthermore, the target ignition timing ψb for promoting continuous detonation before top dead center,
The target ignition timing ψa for promoting the first explosion after top dead center is set as a time cap, that is.

Here, the delay times tl and t2 from the generation time ψO of the reference signal are determined (see Fig. 2).

Step a8. When step alo is reached after a9, other controls of the engine, such as a fuel injection amount calculation routine, an idle rotation speed control routine, etc., are executed.
Return to step a3.

The first interrupt routine is interrupted every 75 degrees before top dead center based on the reference signal changing from off to on.

Here, the latest dwell angles are set in the three one-shot circuits A. Further, a target ignition timing ψb for promoting continuous detonation is set in the one-shot circuit C as the latest target ignition timing.

Thereafter, the CPU calculates the latest engine speed based on the time difference between the previous and current reference signals (off command on), takes it into a predetermined area, processes it, and returns.

The second interrupt routine is interrupted based on the reference signal changing from on to off every 5 degrees before top dead center.

Then, the reference ignition timing ψ1 as the latest target ignition timing (outputted at the same time as the interrupt signal) and the target ignition timing ψa for promoting initial explosion are set in the one-shot circuits B and D, respectively, and the process returns to the main routine.

FIG. 1 shows an output circuit 1, a drive circuit 2 as an igniter connected to the power circuit, a power transistor 3, and an ignition coil 4 used in this embodiment, and FIG. 2 is a timing chart thereof.

The output circuit 1 includes a set changeover switch 5. When the switch is off, the reference signal (ψO at crank angle)
is output only to one-shot circuit B by the function of diode 6, and when the switch is on, one-shot circuit B
, C, and D.

When the set changeover switch 5 is off, that is, during steady operation, the one-shot circuit B is connected to φO (for example, 7
5°) reference signal (off→on),
After counting the crank angle signal (pulses in units of 1" or 2°) a predetermined number (delay time tll corresponding to ignition timing ψ〇-ψt), an energization start signal is output. In this case, the target ignition timing ψt is obtained in step a8 of the flowchart of FIG.

The one-shot circuit A1 is triggered by the energization start signal, counts a predetermined number of crank angle signals corresponding to the dwell angle, and outputs an ignition signal.

Flip-flop 7 is turned on by the energization start signal from one-shot circuit B! - and is reset by the ignition signal from the one-shot circuit A1.

Furthermore, when the flip-flop 7 is in the set state, the drive circuit 2 turns on the switching transistor 3 using its output signal, thereby causing current to flow to the ignition coil 4. In the ignition coil 4, a high voltage current is generated on the secondary side when the switching transistor 3 is turned off, and this current is transmitted to the spark plug by the distributor.
Ignition takes place.

Next, when the set changeover switch 5 is turned on, that is, at the time of starting, the one-shot circuit B is triggered to rise from the base position (off-on) at ψ0 before top dead center, and the crank angle signal (1° or pulses in units of 2°) to a predetermined number (
After counting the delay time tl corresponding to the ignition timing ψ0-ψb, the energization start signal is output. The target ignition timing ψb in this case is step a9 of the flowchart in FIG.
This is what was asked for.

The one-shot circuit A1 is triggered by the energization start signal, counts a predetermined number of crank angle signals corresponding to the dwell angle, and outputs an ignition signal.

The flip-flop 7 is set by the energization start signal from the one-shot circuit B, and reset by the ignition signal from the one-shot circuit A1, and after energization at the dwell angle during that time, ignition is performed at the target ignition timing ψb for promoting repeated detonation. It performs processing.

Furthermore, one-shot circuits C and D are operated at ψ1 before top dead center.
(e.g. 5°) and crank angle signal (1° or 20 unit pulses)
(Here, the ignition timing ψ1−ψ1, that is, 0
, and the delay time O corresponding to the ignition timing ψ〇−φa
and t2) and then outputs each energization start signal.

The target ignition timings ψl and ψa in this case are those determined in step a9 of the flowchart of FIG.

The one-shot circuit A2 is triggered by the energization start signal of the one-shot circuit C, and the one-shot circuit A3 is triggered by the energization start signal of the one-shot circuit, and counts a predetermined number of crank angle signals corresponding to the dwell angle. , which outputs an ignition signal.

The flip-flop 8 is set by the energization start signal from the one-shot circuit C, and reset by the ignition signal from the one-shot circuit A2.

After energizing the dwell angle during that time, the standard target ignition timing ψ1
Then, the flip-flop 9 is set by the energization start signal from the one-shot circuit A3, and reset by the ignition signal from the one-shot circuit A3, and after the dwell angle energization in the meantime, the flip-flop 9 is set by the energization start signal from the one-shot circuit A3. Ignition processing is performed at the target ignition timing ψa for accelerating detonation.

(Effect of the invention) By performing the ignition process multiple times before and after top dead center, both the ignition process for promoting the first detonation and the ignition process for promoting the continuous detonation are performed, so the first detonation and the subsequent continuous detonation continue. , it is possible to improve the startability of a spark ignition engine when it is cold.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of the output circuit used in one embodiment of the present invention, FIG. 2 is a timing chart of the same circuit, and FIGS. 3 to 5 are the main routine of the CPU used in the above embodiment and the first ．． a flowchart showing a second interrupt routine;
FIGS. 6(a) and 6(b) are characteristic diagrams of in-cylinder gas temperature and initial explosion and complete explosion of a spark ignition engine. DESCRIPTION OF SYMBOLS 1... Output circuit, 2... Drive circuit, 5... Set changeover switch, ψb... Target ignition timing for promoting continuous explosion, ψa... Target ignition timing for promoting first explosion. Form a mouth 4 圀弗口

Claims (1)

[Claims] This method determines the ignition timing according to the operating conditions of the spark ignition engine and ignites the engine. Only when starting the spark ignition engine, each cylinder of the engine reaches the top dead center, A multiple ignition control method at startup, characterized by performing ignition processing multiple times.