Electronic Ignition
Capacitive Discharge Ignition ( CDI )
Transistor Controlled Ignition ( TCI )

This guide explains the basic principals and theory behind electronic ignition.
This is linked from the (Yamaha Vision Motorcycle Ignition FAQ) & my (Vision Home Page).
If you have inputs to this page .... PLEASE email Dave "Leather" Draper [email protected]

Last Update June 20005. Download This Guide As PDF (Zipped File)





Intro

This guide was started for a motorcycle group seeking to solve common ignition problems. But over time, this has expanded into this stand-alone page because of the interest for a general explanation of gas 4-stroke (not diesel or 2-stroke) engine ignition principals. Everyone at one time or another has suffered through some ordeal caused by a non-working ignition system. Whether its the lawn mower, outboard, chainsaw, or the time you drove your Dad's car through that big puddle..... you've been stuck somewhere or with something that would not run. When troubleshooting non-running engine problems I've always used the "GAS" method : "gas, air, spark". Have those 3... something should happen. So this is a discussion of how we get the Spark part.





Review of basic ignition designs

Basic Points/Distributor/ Coil.
("Kettering" design)


A Frenchman named Etienne Lenoir invented the electronic spark plug in 1860. Spark plugs haven't really changed THAT much since then. But "firing" that spark plug has been a better evolution. The Father of ignition is Charles Franklin Kettering (man pictured left). In 1909, Kettering, in association with Edward A. Deeds, organized the Dayton Engineering Laboratories Company (Delco). As you've already started to guessed from the name... they invented the first automobile generator. That road to the generator invention brought them all the design concepts that would be used to dream up starter motors, ignition system components, etc.. So, it is in 1910 that Kettering began work on new automobiles electrical systems. Also notably, he invented the first "self-starter" in 1912. Within two years, most cars were equipped with this new device. Kettering went on to become head of General Motors research laboratories and Vice President of the Corporation. "Boss Ket" would eventually receive over 160 U.S. patents for his ideas.

It is in 1911 that he developed the first electrical ignition system (or at least the design concepts that lead to that invention). These early patents are hard to trace, but a little research shows Kettering invented the "engine, starting, lighting, and ignition system" (Patent 1171055 featured here in PDF). This early type of ignition design is known as the Kettering system (points/condenser/coil) or "induction" system. It became the standard in the automotive industry replacing magnetos. It is rugged and reliable but has drawbacks as you will see. A "lighting coil", "lighting" system is a more tradition term for an auto/motorcycle type self powered generator system. So you and I know Kettering more as the man who invented the first practical engine-driven generator (known as the "DELCO" generator). This was Patent No 1150523.


A basic Kettering Ignition Design

A chain, belt, or gear from the engine drives a "DISTRIBUTOR". Inside this distributor is a spring loaded contact switch ("POINTS") riding on a revolving cam. The points would open and close to fire a single coil which would produce the spark for the spark plugs. Inside the distributor is also a "ROTOR" which rotates to determine which plug wire gets the spark.


A.To Coil

B. Points

C.Points Dwell Adjustment

D. Point Riding On Cam

E. Rotating Cam Driven
.....by engine

F. Condensor





Magnetism and Induced Current

In the mid 1800's Michael Faraday (and others ... though "micro Farads " to this day is the measurement of capacitance) developed the concept tha

 

http://www.jetav8r.com/Vision/Ignition/CDI.html
this is the original link take allok at the pictures and stuff.