Development of Anti-Plug Fouling Ignition System 920575

The new generation engines currently being developed tend to require cold type spark plugs, which are prone to fouling.

This paper describes the development of a new Coil on Plug ignition system that resolves this problem by using the high energy and the fast secondary voltage rise time of a capacitive ignition while maintaining inductive ignition characteristics for good ignitability. To evaluate the effectiveness of the system, spark plug insulation resistance was monitored and cold tests were conducted. The results demonstrated that the new ignition system is remarkably effective: insulation resistance remains high and startability and driveability are unaffected under conditions normally leading to excessive misfires and failure to start with a conventional inductive system.

To satisfy environmental concerns, automobile manufactures are increasingly turning to high compression ratio engines in view of their improved performance. In addition new two-stroke engines and FFVs (Flexible Fuel Vehicles) are being developed. For various reasons, these engines require cold type spark plugs: high compression ratio engines operate at higher temperatures, two-stroke engines fire twice as often and FFVs tend to suffer from pre-ignition when operated on methanol fuel.^{[1] [2]} Unfortunately cold type spark plugs are susceptible to fouling. There is therefore a great need for a new ignition system that will prevent plug fouling. This paper describes the development of an ignition system designed to fulfill this need and evaluates the performance of the resultant system.