Browse Publications Technical Papers 1999-01-3323
1999-09-28

Real-Time Air/Fuel-Ratio Control in a Small SI Engine Using the Ionic Current Signal 1999-01-3323

Experiments were conducted on a small SI engine with the objective to investigate the relationship between air/fuel-ratio and the ionic current signal measured across the spark plug electrodes. The propane-operated, single-cylinder engine has been equipped with sensors to monitor its operating conditions and a CDI ignition system with a built-in ionic current sensing circuit.
More than 50 features of the ionic current signal have been examined in a preliminary analysis. Three features of the cycle-averaged signal (signal peak, signal integral in a crank angle window around the peak position, signal amplitude after a preset delay) were found to correlate reasonably well with air/fuel-ratio for the full range of operating conditions. After an evaluation of cycle-to-cycle variations of these features, simple algorithms for an application of the ionic current - mixture strength relationship are introduced.

SAE MOBILUS

Subscribers can view annotate, and download all of SAE's content. Learn More »

Access SAE MOBILUS »

Members save up to 43% off list price.
Login to see discount.
Special Offer: With TechSelect, you decide what SAE Technical Papers you need, when you need them, and how much you want to pay.
X