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With the development of engine management; ignition coils have undergone a complete redesign. So, the traditional oil/asphalt filled; barrel shaped coils have died. As a result, virtually all manufacturers, use resin filled plastic coils. They are smaller, lighter and more efficient. But, regrettably they are not always more reliable.
Consequently, when a voltage is passed through it; a magnetic field is generated around the windings. If the voltage is interrupted (switched off); the magnetic field collapses. As a result, generating a voltage in the secondary windings. This generated or induced voltage; is dependent upon; the ratio of the windings (primary to secondary). Not to mention, the voltage turning on and off quickly.
The switch is opened and closed by contact points. Consequently, just before the piston reached top dead center. During the late 70’s and early 80’s electronic ignition; replaced the mechanically operated contacts. This enabled a faster switching speed (hence higher voltage output). And, more accurate ignition timing settings.
Electronic ignition used a non-contact sensor (hall or inductive type); that was the forerunner to today’s cam/crank sensors.
So, with engine manufacturers designing more and more powerful engines; the need arose for higher voltage ignition systems. High cylinder pressures; high combustion chamber temperatures and a lean mixture; all make it difficult for the spark to jump across the plug gap. As a result, requiring a higher voltage. The most demanding applications include turbo/supercharged; lean burn or direct petrol injection applications. Following the advent of electronic ignition; designers turned to developing the ignition coil.
At this point, the traditional ignition system, had reached its limit. Because, it became “saturated” at the higher voltages. The higher voltages required to trigger the spark; also caused other problems. With high tension lead insulation; both voltage and emission interference. As a result, the ignition system had a new design. Also, leading to the development of resin filled plastic coils.
The last few decades have seen, great improvements in ignition technology. As a result, various new ignition coil types have been developed.
Depending on the age; engine design and the ignition system; any of these ignition coil designs might be used:
In older vehicles and vintage cars; you might still ﬁnd what is commonly known as; a can-type ignition coil.
For this type; the induced high voltage reaches the individual spark plugs; via a mechanically driven distributor mechanism.
The Ignition block contains several ignition coils. This ignition coil type is available with; single or dual spark technology.
Pencil or coil on plug ignition coils
So, the spark plug has the coil mounted on top of it. The high voltage pulse is fed; straight to the spark plug; minimizing power loss.
Ignition coil pack systems
So called ‘coil packs’; combine a number of pencil ignition coils mounted within a single component; known as a ‘rail’.
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