Delphi has recently published a number of technical papers that discuss the required advances in key areas to cost-effectively meet the requirements of the next generation of diesel engines.
“Until there is a step-change in powertrain technology, the high energy content of Diesel fuel means that for many applications, Diesel will continue to enable best-in-class fuel economy and CO₂,” explained Martin Verschoor, vice-president engineering, powertrain systems. “Delphi’s papers look at the most critical areas necessary to make further significant improvements, particularly in the highly-dynamic driving conditions typical of the next emissions regulations, and at how to maintain that precision throughout the lifetime of the vehicle.”
Delphi’s closed loop control system using ‘switch’ technology is thought to be a world-first, offering real-time control data that is more precise, more robust and provided by more cost-effective technology than any other existing closed loop solution. The Delphi system detects when the nozzle needle touches the seat or the lift stop, allowing the system to constantly recalibrate all fuelling events over the lifetime of the vehicle as well as compensating for any part-to-part variation. Rather than using pressure sensing systems which require complex data processing with several additional wires on each injector but which are not able to effectively detect multiple injections, the Delphi’s technology is purely electrical using only one additional wire, sensing the needle contact on the nozzle body for each individual injection event.
The company’s research engineers have also been looking at ways to increase their understanding of fuel flows and spray patterns during the opening and closing of injector nozzles. “A significant fraction of the fuel is injected while the needle is moving and at low needle lifts, but to-date most research has been on steady state, fully open conditions,” explained Verschoor. “We will be presenting a paper that discusses the development of new measurement techniques that will help us understand this critical area, making a significant contribution to the enhancement of both injector function and nozzle design.”
These two developments are central to providing the very precise control of fuelling that will lead to further improvement in fuel economy and emissions during the highly transient events typical of real-world driving. “To make the most of the capabilities they offer, we must also extract additional benefits from our proven model-based software by adding new capabilities that allow further optimization of engine calibration for highly dynamic real world driving,” added Verschoor.
Verschoor says the optimized engine calibration methodology being developed by Delphi and its partners will allow calibrations for highly transient real-word driving to be developed more efficiently. In order to control emissions during the more aggressive transient events typical of RDE and WLTP, model-based software control structures with a new engine calibration workflow is required. A further paper will describe this novel approach and show how Delphi has achieved improvements in transient performance, calibration time and robustness.
Delphi’s team will also look at how improvements in the efficiency of SCR for commercial vehicles is opening additional strategy choices that have significant implications for fuel injection system design. The paper on this topic will look at the company’s next-generation fuel system for commercial vehicles, which is centred around two core modular elements: a new patented injector architecture made possible by further miniaturisation of the proven three-way control valve employed today, and a new modular pumping element, developed for efficiency and packaging flexibility. This approach provides significant improvements in both control and consistency, high pressure operation beyond 3,000 bar with close to zero leakage, ultimately delivering improvements in fuel consumption, emissions and noise with less need to compromise between the three objectives.
June 28, 2016