Car ignition system - Assignment Example

The coil consists of an iron core that is laminated, surrounded by two copper coils. The iron core does not create a closed loop on the windings, forming a magnetic circuit that is open, unlike in the case of transformers. The energy stored in the core magnetic field is then transferred to the spark plug. The primary core winding turns are of heavy wire and are relatively few. The secondary core winding are of smaller wire and consists of several thousands of turns. The wires are insulated by enamel and oiled paper since they carry very high voltages.

The coil is normally inserted in a plastic case or a metal can with insulated terminals. Two types of coils are used in Volkswagens; the Black coil and the blue coil (Vidler & Knowles, 2003). The table below shows the comparison of the two types of coils. High tension lead wires are used to connect an ignition coil, a distributor and magneto to the spark plugs. Each of the leads contain a single wire since the current does not come back through the same path, but through the grounded engine connected to the negative terminal of the battery.

A spark plug lead should have a resistance range of between 14 to 16Kohm/meter (Bolton, 2005). When the ignition switch is closed, current from the battery builds up inside the primary winding of the coil. However, the inductance of the coil prevents instant flow of current. The flow of current inside the coil produces a magnetic field around the core. Current must be allowed to flow long enough in order to store sufficient energy for the spark. Once sufficient energy is built, the contact breaker is opened, and since it is connected to a capacitor, the capacitor and the primary winding form a tuned circuit.

The oscillation of the stored energy between the capacitor and the inductor of the coil initiates changing of magnetic field in the core of the coiling