Development of a New Light Stratified-Charge DISI Combustion System for a Family of Engines With Upfront CFD Coupling With Thermal and Optical Engine Experiments

A new Light Stratified-Charge Direct Injection (LSC Dl) spark ignition combustion system concept was developed at Ford. One of the new features of the LSC Dl concept is to use a 'light' stratified-charge operation window ranging from the idle operation to low speed and low load. A dual independent variable cam timing (DiVCT) mechanism is used to increase the internal dilution for emissions control and to improve engine thermal efficiency. The LSC Dl concept allows a large relaxation in the requirement for the lean after-treatment system, but still enables significant fuel economy gains over the PFI base design, delivering high technology value to the customer. In addition, the reduced stratified-charge window permits a simple, shallow piston bowl design that not only benefits engine wide-open throttle performance, but also reduces design compromises due to compression ratio, DiVCT range and piston bowl shape constraints.