Search Results

This paper describes the dynamometer development of a lightly stratified direct-injection spark-ignition engine. The engine was designed for stratified charge operation at speeds and loads below 2000 RPM, 2 bar BMEP. Test results detailed in this report include evaluation of part-load stratified-charge, part-load homogeneous-charge, and WOT operation. The program had aggressive goals in improving WOT performance and part-load fuel consumption compared to a baseline PFI engine while meeting Stage V emissions levels. Mini-map analysis of the engine data indicated that the engine was able to meet the emissions and fuel consumption goals.

A new Light Stratified-Charge Direct Injection (LSC DI) spark ignition combustion system concept was developed at Ford. One of the new features of the LSC DI 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 DI 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.

This report describes the dynamometer testing portion of the combustion system development of a direct-injection stratified-charge gasoline engine. The engine used in this study is a single-cylinder, direct-injection engine with a newly designed cylinder head comprised of 4-valves per cylinder, an intake-side-mounted DI fuel injector and a bowl-in-piston wall-guided stratified-charge combustion system. Test results detailed in this report include evaluation of four piston designs, two combustion chamber designs, and two injector spray angles. Tests were run at stratified-charge part-load, homogeneous-charge part-load, and WOT conditions. The program had aggressive goals in improving both WOT performance and part-load fuel economy while achieving Stage IV emission requirements. Tests results showed that the engine was able to meet these program goals.