A new dynamic combustion control based on in-cylinder conditions for diesel engines

A model-based combustion prediction controller was developed to carry out control operations while predicting ignition based on the physical condition inside the cylinder. This model calculates the intake gas O2 fraction without a delay similar to measurement by the O2 sensor. It calculates the O2 content of the EGR passage outlet gas by taking into consideration the transfer of gas inside the passage for each intake stroke. Then it calculates the O2 content of the intake gas that is mixed with EGR gas according to the EGR ratio. The ignition timing control was implemented and its control precision was verified. In order to carry out the calculations within the time limit required for the cycle-by-cycle control operation, a purpose-built high-speed ECU was used. By predicting and controlling the ignition period through observation of the physical condition inside the cylinder, misfire during changes in driving conditions can be prevented in advance, and the torque response as well as any increase in emissions can also be controlled.