DETROIT – How to get fuel-saving diesel engines to comply with ultra-tight U.S. federal and California emissions standards has become the auto industry’s cause celebre in the wake of $3-per-gallon gasoline and ongoing calls for reducing reliance on foreign oil.
At this week’s Convergence 2006 Transportation Electronics Conference, megasupplier Denso Corp. says it is leveraging advanced electronic engine controls and high-speed, high-pressure fuel injectors for a next-generation fueling system that will help diesels breathe in compliance with the latest emissions regulations.
Denso engineers presenting a technical paper here describe their next-generation “C-Series” diesel engine control unit, which mounts directly to the engine, and incorporates the huge processing power required to govern a common-rail fueling system capable of delivering an astounding nine individual injection “events” per cylinder.
Denso says the potential to have as many as nine injection events means an interval between injections as brief as one microsecond.
A Denso engineer tells Ward's the unprecedented nine possible injection events come from splitting the typical pre-, main, and post-injection events into as many a three individual injection events. He says the main advantage from this injection philosophy is emissions reduction.
Along with the powerful new ECU and high-speed piezo-hydraulic-electric fuel injectors, the common-rail fueling system develops injection pressure of 29,000 psi (2,000 bar).
Current Denso diesel-engine ECUs incorporate “small-quantity injection learning” software that tailors each injection event based on numerous engine-operation parameters.
The Denso engineers say their upcoming third-generation Diesel Engine Management System, or D-EMS, improves upon that model-based software with new “mean-injection quantity learning” and “reactive-injection quantity learning.”
These ensure the precise injection control required to enable a passenger-vehicle diesel to comply with the low particulate and oxides of nitrogen emissions dictated by the latest U.S. federal Tier II, Bin 5 and California LEV II emissions regulations, which phase in beginning with the ’07 model year.
The D-EMS also incorporates a number of advanced, ultra-precise electronic sensors, including a crankshaft angle sensor accurate to just one-half degree of crankshaft rotation.
Denso does not say when it will have its new D-EMS ready for production, or which auto maker will be the first to employ it for a diesel engine powering a U.S.-market vehicle.