Student Learning Objectives:
- List the primary purpose of an ignition system
- Identify the components of a typical magneto system and describe the function of each part
- Describe small engine ignition advance system
- List the advantages of a solid state ignition system
- Identify three general classifications of magneto ignition systems and explain the operation of each
- Describe why an ignition system requires high voltage
Essential questions
- What does it mean to time an engine?
- What does it have to do with BDC and TDC?
- Why does a small gas engine fire on every rotation?
- How does the engine know when to fire?
What's the point?
The purpose of an ignition system is to provide sufficient electrical voltage to discharge a spark between electrodes of a spark plug.
The timing of this spark is also very very important. The spark must occur at exactly the right time to ignite the highly compressed air-fuel mixture. We have previously discussed that the spark should occur just before TDC or top dead center. This allows for the fuel to be ignited just before that piston is going to pass TDC and continue on to the power stroke.
The timing of this spark is also very very important. The spark must occur at exactly the right time to ignite the highly compressed air-fuel mixture. We have previously discussed that the spark should occur just before TDC or top dead center. This allows for the fuel to be ignited just before that piston is going to pass TDC and continue on to the power stroke.
The basic components
- Permanent magnets
- High tension coil (primary and secondary windings)
- Mechanical or electronic switching device
- Condenser (only on mechanical systems)
- High tension spark plug wire
- Spark plug
