synchronized multi spark

Posted on Feb 5, 2014

Shaping block has the role to provide fixed length impulses (2 mS) at each breaker-points opening. In this way are eliminated the false impulses which appear due contacts vibrations. As shown in drawing, shaped impulse triggers directly the EID and act as START impulse for multi-spark module. If rpm of engine is under speed limit, the module will

synchronized multi spark
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generate a series of supplementary impulses that, through an OR gate, will generate supplementary sparks by EID. When speed limit is reached (for example, 2000 rpm), supplementary impulses stops at module output, thus no supplementary sparks will be generated. The module uses for control the shaped impulses from breaker points. The time between two consecutively impulses depends on rpm engine and has the values shown in upper table. From whole T interval, only in the first half of this will be generated supplementary sparks, after the main spark produced by the breaker points. This is very important, because generating sparks outside of half of the interval, the spinning distributor could apply these sparks to next cylinder, and this could be very harmful for mechanical parts of engine. At breaker-points opening, the shaping circuit (not shown in drawing) produces a square impulse having 2 mS. This, named BP, is applied to EID by an OR gate and generate the main spark. In multi-spark module, during 2 mS interval, a sequence timer (a counter with decoded outputs) accomplishes the initialization of circuits (full operations will be detailed later). When impulse BP disappears, the gate P2 is opened and the counter N1 receives impulses with 1 mS period, from clock generator. This 8 bits counter measures, in fact, the duration between two breaker-points impulses. It can count maximum 255 impulses, each having 1 mS (see the...

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