JPH09209898A - Method for controlling engine ignition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the same effect that spark duration is lengthened so as to improve ignitionability without performing such a change that the capacity of a condenser is increased, by generating plural times a trigger signal for operating switching means in wave length shorter than one period of the discharge corrugation of the condenser. SOLUTION: A pulser coil 4 is connected to a pulser input terminal PU, and a spark advance reference signal inputted to this terminal PU becomes a positive/negative pulse signal through a corrugation shaping circuit 8, and inputted to the input terminals I1, I2 of a CPU. When a trigger signal is outputted from the output terminal O1 of the CPU 9, a thyristor SCR is switched ON so that a main condenser C1 starts discharging, and current is applied to a primary side coil 5a, then the voltage corrugation of a terminal IG is formed into a resonance corrugation (AC corrugation). At this time, the trigger signal is set shorter than one period of the resonance corrugation, the resonance corrugation is stopped by generating the part of one period, and a second trigger signal is generated after lapse of set suspending time.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an engine ignition control method in which a capacitor is discharged by a trigger signal and ignition is performed by an ignition coil.

[0002]

2. Description of the Related Art Conventionally, for example, there is a CDI system in an ignition device for an internal combustion engine of a two-wheeled vehicle, which generates an AC arc in which positive and negative voltages alternately appear in discharge of a plug. In such an ignition device, there is one in which a capacitor is connected in series to the primary side of an ignition coil and a thyristor turned on by a trigger signal whose lead angle is controlled discharges the capacitor.

In the above ignition device, as shown in FIG. 3, an ignition signal is generated once for a predetermined time T. From the time of generation of the ignition signal, a voltage waveform as shown in the figure occurs on the primary side of the ignition coil,
AC arc is generated. This voltage waveform is a waveform that gradually decreases as shown in the figure, and almost disappears after a lapse of time t.

[0004]

By the way, in order to improve the ignition characteristics in the engine ignition control, the capacity of the capacitor is increased to increase the ignition energy, the charging voltage of the capacitor is increased, or the ignition coil is operated. There is a method of increasing the primary inductance to lengthen the duration of the spark (the above time t).

However, in order to increase the capacity and voltage of the capacitor, not only the capacitor but also the thyristor, the diode and the converter must be reinforced, and in order to increase the primary inductance, the ignition coil becomes large. Therefore, there is a problem that the cost increases in any case. Also, C
There is also a problem that the current consumption of DI increases.

[0006]

In order to solve such a problem and to improve the ignition characteristics without increasing the size of the device, the energy stored in the capacitor is ignited by the ignition plug. It is necessary to supply with an appropriate size and time in accordance with the expansion of the flame kernel as energy,
In the present invention, in the engine ignition control method for performing ignition control by discharging the capacitor connected to the primary side of the ignition coil by operating the switching means by the trigger signal output from the control means, The trigger signal is generated a plurality of times at a wavelength shorter than one cycle of the discharge waveform of the capacitor.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below in detail based on specific examples shown in the accompanying drawings.

FIG. 1 is a circuit diagram of an essential part showing an engine ignition device of a motorcycle to which the present invention is applied. As shown in the drawing, the battery 2 is connected to the voltage terminal BT of the CDI circuit 1, and a pulsed advance reference signal can be generated at the pulser input terminal PU in response to the rotation of the AC generator 3, for example. Is connected to the pulsar coil 4 provided in the. Further, the primary coil 5a of the ignition coil 5 is connected to the output terminal IG. The ignition plug 6 is connected to the secondary coil 5b of the ignition coil 5.

In the CDI circuit 1, the DC-DC converter 7 and the main capacitor C1 are serially connected in this order on the power supply line from the terminal BT to the terminal IG. Therefore, the main capacitor C1 is connected to the primary coil 5a of the ignition coil 5 via the terminal IG. Further, the lead angle reference signal input to the terminal PU becomes a positive / negative pulse signal via the waveform shaping circuit 8, and each input terminal I1.
Input to I2 respectively.

A diode D1 and a thyristor SCR are connected in parallel to each other on a voltage line from the DC-DC converter 7 to the main capacitor C1 and are grounded. The thyristor SCR is driven and controlled by a trigger signal from the output terminal O1 of the CPU 9. A capacitor C2 is connected between the gate of the thyristor SCR and the ground line.

When the thyristor SCR is turned on, a current flows from the main capacitor C1 through the thyristor SCR to the primary side coil 5a via the ground line, and from the primary side coil 5a to the ground line via the diode D1. A current flowing in the direction of reaching the capacitor C1 alternately flows, and a spark having an AC waveform is generated in the spark plug 6.

Next, the control procedure by the CPU 9 according to the present invention will be described below with reference to FIG. When the trigger signal as shown in the upper part of FIG. 2 is output from the output terminal O1 of the CPU 9, the thyristor SCR is turned on, the charged main capacitor C1 starts discharging, and as described above, the primary coil A current flows through 5a, and the voltage waveform at the terminal IG becomes a resonance waveform (AC waveform) as shown in the lower part of FIG.

In the present invention, the trigger signal is shorter than one cycle of the resonance waveform, and the resonance waveform is generated for one cycle and stopped as shown in the lower part of FIG. Then, the second trigger signal is generated after the preset pause time T1 has elapsed. Further, if necessary, after the resonance waveform for one cycle is generated by the second trigger signal, the third trigger signal may be generated after the rest time T2 has elapsed.

Since the sparks are generated intermittently in this way, the same effect as that of increasing the duration ta of the sparks (> t) can be obtained without increasing the energy for generating the sparks. . Further, since the generation timing of the trigger signal is controlled by the CPU 9, the pause times T1 and T2 and the number of times the trigger signal is generated can be easily changed without providing a circuit for setting the time constant. As a result, optimal and efficient ignition can be performed with respect to the spread of the flame kernel of the plug portion, which changes depending on the engine speed, temperature, acceleration state, and the like.

[0015]

As described above, according to the present invention, the duration of the spark is lengthened by only changing the timing of generating the trigger signal in the conventional circuit without changing the capacitance of the capacitor. The same effect can be obtained and the ignitability can be improved. As a result, it is possible to contribute to improving the fuel efficiency of the vehicle and cleaning the exhaust gas.

[Brief description of drawings]

FIG. 1 is a circuit diagram of a main part showing an engine ignition device of a motorcycle to which the present invention is applied.

FIG. 2 is a time chart showing a control procedure according to the present invention.

FIG. 3 is a time chart showing a control procedure of a conventional engine ignition device.

[Explanation of symbols]

 1 CDI circuit 2 battery 3 AC generator 4 pulser coil 5 ignition coil 5a primary coil 5b secondary coil 6 spark plug 7 DC-DC converter 8 waveform shaping circuit 9 CPU

Claims (1)

[Claims] 1. An engine ignition control method for performing ignition control by causing a capacitor connected to a primary side of an ignition coil to be discharged by operating a switching means in response to a trigger signal output from the control means. An engine ignition control method, wherein a signal is generated a plurality of times at a wavelength shorter than one cycle of the discharge waveform of the capacitor.