Relationship Between Local Air-Fuel Ratio and Combustion Character in Spark Ignition Engines

The authors developed a method to measure the air-fuel ratio at local points within the combustion chamber. The primary point is to obtain the pre-combustion air-fuel ratio of the mixture from the HC (vaporized fuel) and O2 concentrations. This procedure which consists of three parts, gas sampling, gas transport and gas analysis, renders it possible to perform direct quantitative HC analysis of samples.

This method is carried out by either of two techniques: multi-cycle sampling (MCS) and single cycle sampling (SCS), and the average air-fuel ratio of many engine-cycles and the single engine-cycle were obtained respectively.