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26/05/2011
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Iveco and FPT Industrial say they are ready to meet Euro 6 emissions regulations for medium- and heavy-duty trucks, using SCR (selective catalytic reduction) alone.
 The technology will, they say, be introduced on two new Cursor and Tector engine ranges for trucks and buses, which will both feature no EGR (exhaust gas recirculation), to maximise burn efficiency.
Details are sketchy, but the 'SCR only' technology features "optimised combustion and after-treatment systems" using "breakthrough patented control technology in which a very high NOx conversion efficiency [over 95%, compared with 80—85% at best] is achieved".
"We were the first to announce our Euro 6 engine technology strategy back in April 2010," says Iveco CEO Alfredo Altavilla.
"I said then that we would meet Euro 6 standards without EGR [exhaust gas recirculation]. EGR has its place, but for heavy commercial vehicles … the technology that reduces fuel and operating costs to a minimum is the correct choice.," he continues.
"FPT Industrial's 'SCR Only' exhaust after-treatment fulfils this important need. It is clear that Euro 6 vehicles will be more expensive. We will introduce suitably equipped vehicles when our customers ask us to do so."
Iveco, he says, is exploiting "technological strides" taken by FPT to further improve the efficiency of SCR technology, which allows "unprecedented [NOx] reduction efficiencies".
Reading between the lines, it appears that the significant SCR improvement comes from a new generation of Zeolite based, compact SCR unit, with improved AdBlue dosing (using turbulence mixer technology) and thermal management, as well as better sensing and feed-forward control. The developments, they say, follow fluid-dynamics modelling of exhaust gases and AdBlue injection on SCR catalysts.
Beyond those, Iveco also cites its high cylinder pressure and injector nozzle pressures (up to 2,200 bar), which have been achieved through changes to the crankcase and cylinder head designs that together make for increased structural rigidity, higher coolant flows and increased swept volumes.
A new electronic control unit has also been introduced to manage both engine parameters and after-treatment control, integrating engine, SCR and full-flow DPF (diesel particulate filter) functions.
For Cursor engine versions using the variable geometry turbocharger, electronic control has also been introduced to optimise load response at low engine speeds and to increase the effectiveness of the engine brake. Also, all engines will now harness flap type engine brake valves to support passive DPF regeneration and improve engine brake performance by up to a claimed 30% compared to current Euro 5 engines.
Incidentally, to prevent any oil mist carried in engine blow-by gases, very high performance oil separation systems have been introduced –important to prevent oil burning and consequent DPF contamination. For Cursor engines, an oleophobic centrifugal oil separation has been implemented, while for the Tector, a high efficiency valve cover integrated coalescent type blow-by filter is being used.
As for the box itself, Iveco talks of a compact SCR after-treatment system with all components integrated and designed to optimise layout and minimise weight. The result is a single box shaped unit, including DOC (diesel oxidant catalyst), DPF, SCR and CUC (clean-up catalyst).
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Author
Brian Tinham
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