Optimization-based fuel injection rate digitalization for combustion rate shaping

A major challenge of diesel engine development is the reduction of pollutant and CO
₂
emissions. For that reason new solutions for clean and efficient combustion are investigated. One promising approach is the so-called combustion rate shaping. In this case the entire in-cycle resolved pressure or combustion rate trace is controlled by manipulating the whole fuel injection rate profile. One substantial task within combustion rate shaping is therefore the realization of the continuously shaped fuel injection rate profile. State of the art series production injection systems do not allow for a continuously shaping of the injection rate profile. Instead a multi-pulse fuel injection pattern with a finite number of injection events is being applied to approximate a continuous shaping. Each of these pulses is parameterized by corresponding actuation timings controlling the start and the duration of the injection event. In this contribution an optimization-based method for the digitalization of a continuous fuel injection rate profile is presented. For this purpose a reduced order injector model is presented. Additionally a suitable optimization problem is derived and presented along with numerical solution techniques.