Ignition System Flashcards
What is the main function of the Ignition System?
The Ignition System turns a spark ignition engine on or off, produces a high voltage arc at the spark plug, distributes high voltage to each spark plug in the correct sequence and times the spark.
What Voltage is supplied by the Battery and what Voltage is supplied by the Alternator?
The battery supplies direct current, while the alternator supplies alternating current.
What voltage is typically produced by the Ignition System?
Direct Current
What is the purpose of the Ignition Coil and how does it work? 3 steps.
The ignition coil is a step - up transformer, which steps up the voltage from the battery and produces short bursts of high voltage, which is sent to the spark plug to start combustion.
- The current flows from the battery through the primary windings, where a strong magnetic field is generated.
- The iron core helps to concentrate this magnetic field.
- When the current is interrupted, the magnetic field collapses across the secondary winding and up to 60,000 volts is induced.
What is the Primary Circuit and what is the Secondary Circuit?
The primary circuit is between the battery and the ignition coil. It operates on low voltage of 12-15 volts. The secondary circuit is between the ignition coil and the spark plug. it is a high voltage circuit that conducts voltage between 4,000 - 30,000 volts and includes wires and parts between the coil output and spark plug ground.
What are the Two purposes of the Ignition Distributor?
- Controls the on/off cycle of the primary coil.
- Distributes high - voltage t spark plugs and controls the timing of the spark in relation to the engine’s speed and load.
List the parts of the Ignition Coil.
- Primary Coil Winding.
- The Secondary Coil Windings.
- The Iron Core.
What are the Four types of Ignition Distributors?
- Contact point, 2. Pickup Coil, 3. Hall - effect, 4. Optical.
Explain Primary Dwell Period and Ignition Dwell Ending.
The Primary Dwell Period is when the current flows from the battery through the coil primary windings and where the magnetic field builds up around the primary windings.
The Dwell Ending - Ignition: when the switching circuit opens and current flow stops. The magnetic field collapses across the secondary coil windings and a high burst is sent to the spark plugs.
Explain Wasted Spark Ignition.
Each end of the coil’s secondary winding is connected to a spark plug. This is where two spark plugs are fired at the same time as they are fired in pairs. High voltage forces current flow through two wires, firing each plug with opposite polarity. One spark plug fires during the compression stroke, the other during the exhaust stroke, wasting the voltage produced for that spark plug.
Explain Direct Ignition.
Direct Ignition has a separate ignition coil for each spark plug. The high voltage pulse is directly applied to the individual spark plugs. The spark plugs are fired in the firing order of the cylinders.
Which engine component drives the Ignition Distributor?
The Camshaft?
What is a trigger Wheel?
A trigger wheel or reluctor, or pole piece is fastened to the upper end of the distributor shaft. It has one tooth for each engine cylinder.
What is the purpose of the Spark Plug and what is the difference between a hot spark plug and a cold spark plug?
A spark plug uses high voltage to ignite the air- fuel mixture. A hot spark plug has a long insulator tip, is hotter, able to burn debris from its tip and has increased knock. A cold spark plug has a shorter insulator tip, is used in high - speed engines and is colder which reduces knock and prevents the tip from overheating and preignition.
Explain Ignition Timing Advance and Ignition Timing Retard.
Ignition Timing Advance fires the spark plugs earlier, BTDC and gives enough time for combustion to develop pressure on the power stroke. Ignition Timing Retard: the spark plugs fire later and this ignition timing is used in low speed, high load conditions and prevents spark knock or ping.
