The launch follows years of development by Delphi working closely with customers to help them address stringent future emissions requirements.
In the patented Delphi Direct Acting Common Rail system, the injector needle is set in motion directly by a piezo ceramic actuator, rather than being moved via an electro-hydraulic circuit as with existing fuel injection technologies. This enables the injector to spray fuel into the combustion chamber faster and with much improved spray momentum and accuracy and provides extremely fast opening and closing of the needle valve, independent of injection pressure. The resulting improved combustion control provides a considerable reduction in emissions, more torque and power across all engine speeds and significantly improved fuel economy and refinement.
The Delphi Direct Acting diesel common rail system uses a patented Direct Acting concept, where the piezo ceramic actuator directly operates the needle valve of the injector for initial lifts, such as those obtained in pilot injections, and a hydraulic amplifier is used to help complete the lift for large injections.
The concept eliminates the servo-hydraulic circuit that other common rail injectors use. This allows the injector to spray fuel into a diesel engine combustion chamber faster, with greater accuracy and at higher pressures (up to 2000 bar) and with higher efficiency than current injection technologies.
Proportional control of needle lift by the Engine Control Unit (ECU) allowing the rate of injection to be mapped into the ECU. This allows separate optimization of idle noise, emissions and full load performance where as today the rate of injection is controlled by the injector hardware and is a compromise between the three different areas.
To summarise, the system offers improved injection fuel atomization and speed to help reduce emissions and engine noise, while providing unequalled driving performance. Indeed, the Direct Acting Piezo advantages of higher spray momentum and highly flexible multi-injection make it an ideal choice for the next generation combustion systems (i.e. HCCI or PCCI etc.) as demonstrated in SAE tech paper “A Study of Methods to Lower HC and CO Emissions in Diesel HCCI.”