|New generation XL3 injector for GDI engines goes into production. Click to enlarge.|
Continental’s new XL3 high-performance solenoid injector for gasoline direct injection systems is currently in volume production for a four-cylinder, 1.5-liter GDI engine. The XL3 solenoid injector provides enhanced linearity due to very fast opening and closing times and multi-stream spray geometry (max. of 8 holes) enables optimal adaptation to all engine-specific requirements.
The XL3 offers high flexibility of spray characteristics to meet the requirements of side- or central-mounted engines. System pressure ranges from 40 up to 200 bar—50 bar higher than the XL2 injector. Static flow range for the XL3 is up to 20 g/s (at 100 bar at 70 °C); the XL2 had a maximum flow of up to 17 g/s.
Compliance with future emissions standards such as Euro 6b (from 9/2014) and Euro 6c (from 9/2017) will call for further improvements in engine combustion processes. As gasoline engines offer significant scope for reducing emissions through more efficient combustion, downsizing and turbocharging, they will play a significant part in realizing these improvements. The fast-response, high-precision solenoid injector technology prepares the ground for future Euro 6c applications, the company says. Additionally, with further-refined monitoring functions, the XL3 injector can reduce particulate emissions in GDI engines.
The high-performance injectors required for this highly efficient type of engine are currently designed to operate at pressures up to 200 bar.
Building on the level we’ve already reached, we are continuing to work on the XL3 injector with an eye to meeting the stringent requirements of Euro 6c. Precision metering, combined with multiple injection capability, helps to reduce the particulate emissions of GDI engines and can cut the costs of aftertreatment technology.—Wolfgang Breuer, Head of the Engine Systems Business Unit in Continental’s Powertrain Division
The refinements will focus among other things on designing the actuation system for fast injector opening and closing, which is key to ensuring ultra-accurate metering performance, particularly in the small quantity range.
GDI engines require extremely precise matching of the injector characteristics to the engine. The XL3 injector’s Controlled Solenoid Injection (COSI) function continuously monitors the closing rate of the injector needle, said Gunnar Lowack, Head of the Injector Product Line. On the basis of this information, an integrated correction function then ensures compliance with the nominal injection values throughout the lifetime of the injector.
Precision injection control is key in meeting the stringent particulate number and mass emissions limits of Euro 6c; control delivers the required spray preparation and penetration characteristics under all combustion chamber conditions. This precision will become even more crucial in the future, as new test methods such as WLTC (World Harmonized Light Duty Driving Test Cycle) and RDE (Real Driving Emissions) put greater emphasis on transient conditions (load change).
Such dynamic variations in injection and combustion conditions can have a significant effect on fuel consumption, which demands even more of the injectors.—Gunnar Lowack