The SCR – Selective Catalytic Reduction – solution is the alternative approach chosen by Iveco and the majority of medium and heavy commercial vehicle manufacturers. It consists of optimising engine combustion to achieve maximum reduction of the particulate content in exhaust gases. Engine
performance is improved and this leads to lower fuel consumption. To eliminate the percentage of nitrogen oxides in exhaust gases that exceed the limit, first a reducing agent is added to the gases and then these are treated by a catalytic filter in the silencer. This procedure converts the nitrogen
oxides into entirely harmless nitrogen and water vapour. The reducing agent is ammonia, stored in the form of a urea-based aqueous solution and marketed under the brand name AdBlue.
SCR technology means that particulate filtration is superfluous inasmuch as this type of emission is cut down directly during the combustion phase, while the catalytic converter burns up the remaining particulate simultaneous with treatment of the nitrogen oxides.
Again in this case the vehicle weight increases compared with an equivalent Euro 3 version.
Why Iveco decided to adopt the scr system.
The SCR system chosen by Iveco represents the ideal compromise between two fundamental objectives engine designers had set themselves in order to meet customer requirements. On the one hand, improve engine performance to reduce fuel consumption and running costs, at the same time extending the life of engine components; on the other, comply with emission limits established by European authorities to safeguard the environment. Clearly, the progressive reduction in fuel consumption per tonne of goods transported means engines give off less CO2, the gas responsible for warming the planet.
Iveco began studies on SCR reduction in 1994 at its Arbon Research and Development Centre in Switzerland (Iveco Motoren Vorschung) as a member of a consortium created together with other manufacturers. Iveco has also explored the EGR solution and adopted it on the light commercial
vehicle range, given that for this type of use it represents the ideal compromise between various factors (consumption, weight, cost).
Given the high average annual kilometres travelled by medium and heavy vehicles, the benefit obtained by reducing fuel consumption became the top priority. Furthermore, the SCR approach has no negative effect on lubricant quality or the interval between oil changes. In fact the low particulate content in the combustion chamber further extends these intervals. Similarly, the system isn't sensitive to the
sulphur content of diesel fuel.
Unlike EGR technology the SCR approach doesn't require increased use of the engine cooling system.
Everyone knows that high powered vehicles need larger radiators and the size of these poses serious layout problems on heavy vehicles. Also, increasing fan performance drains power and negatively affects fuel consumption.
A chance to anticipate the Euro 5 directive
A basic advantage of the SCR system is that it can satisfy both Euro 4 and Euro 5 emission level requirements, which means Iveco has been able to develop a solution for both emission levels simultaneously. Thanks to the modern architecture of its engines, and especially the electronic control injector pumps operated by a camshaft located directly in the cylinder block, Iveco has been able to develop a new injection system with higher pressures and finer fuel atomisation. For Iveco Cursor engines AdBlue consumption is 4-5% for Euro 4, or around 1.5 l/100 km, and slightly higher for Euro 5. For instance, a urea consumption of 60 l gives an autonomy of over 3,500 km.
The AdBlue injection system has been tested in extreme climate conditions to take into account the physical properties of this additive and, above all, its progressive crystallisation below –11°C. Test campaigns have been organised in Scandinavia and Spain, while numerous customer vehicles are undergoing long-term testing.
So Iveco is ready to offer heavy Stralis vehicles in both a Euro 4 and Euro 5 version simultaneously.
Iveco expects demand for these vehicles will come mainly from countries offering financial incentives for adopting the European Directives ahead of the date fixed for their introduction. Germany, Switzerland and Austria are good examples.
Iveco Euro 4 and Euro 5 models available before relevant mandatory dates
Euro 4 & 5 models are available before the mandatory dates to adopt the relevant standards, they comply with current regulations (EEC 88/77-EC1999/96-EC 2001/27) and as a priority respond to demand in markets offering financial incentives. These are the models: 4x2 tractors and 6x2 trucks, both available in two engine versions – 430 HP Cursor 10 or 480 HP Cursor 13 – all outfitted with the Stralis Active Space cab. Initial deliveries are forecast for September 2005. Because of heavy demand from Germany and Austria (in general, those countries offering incentives), deliveries for other countries in which road transport operators wish to anticipate the Euro 5 Directive will begin in November this year.