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The modern diesel engine is used around the world to power applications as diverse as passenger cars, heavy-duty trucks, electrical power generators, ships, locomotives, agricultural and industrial equipment. The success of the diesel engine results from its unique combination of fuel economy, durability, reliability and affordability - which drive the lowest total cost of ownership. The diesel engine has been developed to meet the most demanding on-highway emission standards, through the introduction of advanced technologies such as: electronic controls, high pressure fuel injection, and cooled exhaust gas recirculation. The standards to be introduced in the U.S. in 2007 will see the introduction of the Clean Diesel which will achieve near-zero NOx and particulate emissions, while retaining the customer values outlined above.

The paper describes a completely new approach to fully variable valve actuation (FVVA), which allows almost unlimited continuously variable control of intake and exhaust valve opening and closing events, and duration without the use of a camshaft. DigitalAir replaces conventional poppet valves with horizontally actuated valves located directly above the combustion deck of the cylinder head, which open and close a number of slots connecting the cylinder with the intake and exhaust ports, Figure 1. The stroke of the valves to provide the full flow area is approximately 25% of the stroke of the equivalent poppet valve, thus allowing direct electrical actuation with very low power consumption. This design arrangement also avoids the risk of poppet valve to piston collision, or the need for cut-outs in the piston crown, since the valves do not open into the cylinder.

The paper describes a process for the design of fuel-efficient diesel engine powertrains for heavy-duty commercial vehicles. A System Engineering approach is described that delivers optimal fuel efficiency by taking into account interactions among engine, exhaust aftertreatment, and vehicle systems. The primary objective of this approach is to develop a properly integrated system that delivers the lowest total cost of ownership (TCO) while maintaining high sociability, reliability, and performance. The paper will also discuss the role of competitive analysis and benchmarking, in-use duty-cycle analysis, design, simulation and final confirmation tests. System optimization is performed at critical steps in the process for engine hardware, control software and calibration, aftertreatment, engine accessories, powertrain components and vehicle interfaces.