Egr and reformate fraction estimation in a dedicated egr engine

A system to operate a dedicated-EGR engine, the system comprising a controller configured to:

• control provision of a rich air-fuel mixture to a dedicated cylinder;
• control combustion of the rich air-fuel mixture in the dedicated cylinder;
• model the combustion of the rich air-fuel mixture in the dedicated cylinder;
• estimate the composition of the combustion products in the dedicated cylinder based on interpolation of chemical reaction models of stoichiometric and rich combustion;
• estimate a mass fraction of reformate in an intake mixture comprising combustion products from the dedicated cylinder and air;
• estimate a mass fraction of burned gas in the intake mixture;
• control provision of the intake mixture to the intake ports of all of the cylinders of the dedicated-EGR engine;
• control combustion of an air-fuel mixture in a non-dedicated cylinder of the engine;
• control an engine control parameter effective to influence combustion in the non-dedicated cylinder, wherein the value to which the engine control parameter is determined based on the estimated mass fraction of reformate and the estimated mass fraction of burned gas in the intake mixture.

A controller comprising a processor and a non-transitory computer-readable medium containing instructions that, when executed, perform the method comprising the steps of:

• controlling provision of a rich air-fuel mixture to a dedicated cylinder;
• controlling combustion of the rich air-fuel mixture in the dedicated cylinder;
• modeling the combustion of the rich air-fuel mixture in the dedicated cylinder;
• estimating the composition of the combustion products in the dedicated cylinder based on interpolation of chemical reaction models of stoichiometric and rich combustion;
• estimating a mass fraction of reformate in an intake mixture comprising the combustion products from the dedicated cylinder and air;
• estimating a mass fraction of burned gas in the intake mixture;
• controlling provision of the intake mixture to the intake ports of all of the cylinders of the dedicated-EGR engine;
• controlling combustion of an air-fuel mixture in a non-dedicated cylinder of the engine;
• and
• controlling an engine control parameter effective to influence combustion in the non-dedicated cylinder, wherein the value to which the engine control parameter is determined based on the estimated mass fraction of reformate and the estimated mass fraction of burned gas in the intake mixture.