Delphi introduces new generation piezo injectors
2 September 2008
Delphi Corporation is launching high volume production of a next generation diesel fuel injector to be used in the Direct Acting Common Rail system. The new system will be introduced on an undisclosed European production car to be launched later this year.
In the 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, with improved spray momentum and accuracy, and provides faster opening and closing of the needle valve, independent of injection pressure. The improved combustion control provides a reduction in emissions, more torque and power across all engine speeds and improved fuel economy.
The new system uses a patented Delphi 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 used in other types of common rail injectors, solenoid or piezo based.
The new injector can operate at injection pressures up to 2000 bar, allowing seven or more injection events per engine cycle.
The Direct Acting Common Rail system can help meeting future emission standards such as Euro 6 without the need for NOx aftertreatment or with reduced diesel particulate filter volumes, according to Delphi. Noise could be reduced by up to 5 dB(A). The system is also said to be compatible with future HCCI and PCCI combustion modes.
The existing Delphi’s Multec common rail system utilizes injectors with servo-solenoid balanced valve type of actuator, rather than piezo injectors.