Electric, solar-powered and alternate fuel vehicles may be the wave of the future, but for now most automobiles run on gasoline, which they burn in an internal combustion engine to convert into motion.

For combustion to take place, a spark is needed to ignite the fuel mixture in the engine. The vehicle’s ignition system is designed so that a 12-volt battery can generate the very high voltage required to create such a discharge. The heart of this system is a device called an ignition coil.

This coil is a kind of transformer.

Transformers transfer voltage from one circuit to another, either as a higher voltage (as in a step-up transformer, of which the ignition coil is an example), or a lower voltage (a step-down transformer).

The key principle that makes transformers work is electromagnetic induction: A moving magnetic field, or a change in a stationary magnetic field (the case in our ignition coil), can induce a current in a wire exposed to that field.

This ignition coil is a pulse-type transformer. Like other transformers, it consists, in part, of two coils of wire, as shown in the diagram at right. These are both wrapped around the same iron core. Because this is a step-up transformer, the secondary coil has far more turns of wire than the primary coil, which is wrapped around the secondary. In fact, the secondary coil has several thousand turns of thin wire, whereas the primary coil has just a few hundred. In your car, this allows some 40,000 volts of current to be generated by a modest battery.
 

IGNITION COIL

Getting The Spark To Fire The Engine

Alternating current (AC) is used in most types of transformers because the constantly changing magnetic field that it creates in a primary coil allows for a continuous induction in the secondary coil.

In a car’s ignition system, however, direct current (DC) is used (provided by the Battery), because the idea is not to create steady, continuous induction, but one single, dramatic induction from a sudden collapse of a magnetic field.

As current flows to the primary coil, an increasingly large magnetic field builds up around it as well as around the secondary coil housed inside. This rapid change induces a surge of current in the secondary coil, which streams out the high voltage Output Terminal and is enough to jump the Spark Gap in the circuit.

  >> This spark then ignites the fuel mixture and gets the motor running.

There is just one problem with this scenario. The collapsing field also induces a lesser surge (back EMF) in the primary coil, creating a second, unwanted surge of electricity traveling back through one of the primary terminals toward the switch. To keep that surge from reaching the switch (and creating a damaging spark across those points), a Capacitor is inserted in the circuit. This capacitor – called a condenser in auto ignition systems – safely absorbs the back emf.

Comment : The xtreme CHARGER, (among other advantages for enhancing performance) is designed with a special function and ability to help detect the back EMF and allows Rapid Discharge of the "unwanted surge of electricity traveling back through one of the primary terminals toward the switch". This enhancement by the xtreme CHARGER helps to provide Bigger Sparks consistently to improve performance.
 

EMF in Inductors

EMF is an acronym for electromotive force. Scientists tend not to use the spelled-out version of this term, in part because it can be misleading: EMF is not, in fact, a force in the way physicists use the term. Rather, it’s the energy produced by the interaction between a current and a magnetic field when one (or both) is changing. It’s measured in volts, and is sometimes equated with voltage, or potential difference.

To get to a tutorial, click here to understand more about EMF in Inductors >  CLICK

To learn more Electromagnetic Induction >  CLICK

Cost Of Living (what has it got to do with back EMF? Maybe one day we can come to a rationalization.)

Parents : Share with your children if you think this is appropriate. May help their studies, also about cost savings?

 Eg. I live in Upper Bukit Timah
       I made a trip to Changi Village recently
       - Total distance traveled : 80 km (To and Fro)
       - works out to be about 6 litres of petrol (95 octane) - Highway fuel consumption around 13 km/L; which costs around S$12.40
         - that's about 2 sets meal at MacDonald at June 2008 Pricings.

       - if you go around town and get into traffic jams and traffic light stoppages, City fuel consumptions may be 9 km/L!!!
         - you will spend more on petrol per km, as well as paying atrocious parking charges; and hefty ERP charges (another inflationary items, including paying a fix sum (tax) to the government no matter the cost of Oil per barrel)!

       - every time you step on the gas! You are burning $$!

Young People : Parents have to work harder just to maintain Yesterday's Living Standard. Are your studies improving as fast as Cost of Living?