US Patent 7212908 System and method for reducing compression ignition engine emissions

A method of reducing nitrogen oxides (NOx) and particulate matter (PM) in compression ignition engine emissions. The method includes monitoring at least one engine sensor that generates a signal in response to at least one engine operating condition, and adjusting at least one engine control parameter in response to the signal such that in-cylinder spacial distribution of equivalence ratio and temperature is substantially maintained to an operating region. The operating region corresponds to a set of equivalence ratio with respect to temperature values that are substantially outside regions supportive of NOx and PM formation. The temperature values are greater than 1650 K, and the equivalence ratio values are greater than 0.5.