Electronic ignition

A electronic ignition is an evolution of traditional lighting by battery/winds engine spark-ignition .

Traditional lighting

Let us recall that, in traditional lighting, a Rupteur (=vis platinized) opens and is closed according to the angular position of the Moteur, sending the current to a Bobine, which transforms the 12 V of the battery into an impulse of very high tension, allowing the formation of a spark the level of the electrode S of the candle.

Traditional lighting has several disadvantages:

Wear and maladjustment of the Interrupter, causing a loss of performance and requiring interventions
Quality of the average electric impulse

Some explanations:

When the Rupteur (contact points) is closed again, the current in the reel grows exponentially (of zero towards a maximum determined by resistance of the reel) until the interrupter opens. As the current circulating in the reel continues to circulate (it is an inductance), it charges the stray capacity with inductance as well as the series condenser and the tension goes up. It can reach 300 V with the primary education of the reel, which corresponds to 10.000 V with the secondary. This rise is extremely fast, about 10 µs. One then reached the tension of breakdown of 10 Kv at the boundaries of the electrodes of the candle and a spark produced there. This spark is a Electric arc which creates a plasma, which is a good driver of electricity. The tension thus falls very low, a few volts, as well with the primary education as with the secondary. When the current does not manage any more to maintain the arc, the current ceases in the candle and the tension becomes a damped oscillation. This last phase is completely inoperative.

The purpose of the condenser which one puts in parallel on the interrupter is to avoid the production of sparks between its contacts. Indeed, the tension of breakdown is proportional to the distance between the contacts. In the absence of condenser, the tension grows too quickly and it occurs relaxed oscillations produced by a succession of breakdowns between these contacts.

A frequent error is to test a lighting with candles with the free air and to draw a conclusion from it. Indeed, the tension of breakdown is proportional to the pressure. Thus, the tension of breakdown of a candle can vary from hardly 1000 V to the free air to 10 Kv in an engine having a compression ratio of 10.

Concerning this subject, many incorrect information is commonly widespread , primarily because of the great technical difficulty obtaining correct oscillograms. Thus, one could find with the sale of the electronic ignitions with " high tension" (25kV for example) whereas the tension of breakdown cannot exceed 10kV, or of high frequency lightings because the originators believed that the damped oscillations which appear after the end of the arc were useful.

Electronic ignition - amplifier of current

The first generation of electronic ignition consisted in intercalating a breakerless ignition (a kind of Amplificateur) between the Rupteur and the Bobine, so that it sparks less on the level of the interrupter, therefore less wear, and a signal of better quality on the level of the reel.

Electronic ignition with capacitive discharge

Instead of storing energy in a reel, one stores it in a condenser then one applies the tension of the condenser to the reel. This technique has several advantages: not to increase electricity consumption with low mode, it makes it possible to notably increase the energy transmitted to the candle, to lengthen the duration of the spark and to obtain a more complete combustion. The disadvantage of this technique is a greater complexity because of the presence of a converter able to charge the condenser with a tension with 300 with 400V.

Electronic ignition - magnetic detection of the position of lighting

The second generation consisted in replacing the contact points by an electronic sensor (in fact a reel fixes), generating an electric impulse at the time of the passage of a Aimant in front of it. In this assembly, there is no really improvement compared to the preceding assembly, if it is not that there is no more maintenance to envisage on the level of the interrupter.

Complete electronic ignition

The third generation consisted in actually replacing the mechanism of Avance to lighting by an electronic system (, in this case, the system is regulated on full advance ), and a Retardateur electronics puts delay in the situations where there does not need the full advance.

Introduced into the Years 1970, the electronic ignition spread on many categories of engines (Automobile S, motor bikes, etc) starting from the Années 1980.

Many collectors assemble an electronic ignition on old vehicles, making it possible to facilitate starting, to obtain more constant performances and less maintenance, without denaturing esthetics nor the character of the vehicle.

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