The AdBlue tank (standard tank capacity 60 litres, but also available in 45 and 120-litre versions) is located on the right-hand side between the wing and fuel tank. The diameter of the tank tube is small enough to prevent accidental introduction of the diesel nozzle. The AdBlue gun has a valve at the end that is released by magnets located on the tank entry point and so it's impossible to accidentally fill up another tank (for instance, the main fuel tank) with AdBlue. The AdBlue intake duct – a level gauge is also installed on this – is surrounded by a hose in which engine water circulates. Opening of the heating system is regulated by a temperature sensor. The AdBlue filter system includes a prefilter
on the tank and a fine-mesh filter located on the pump intake. The latter is positioned under the rear cab suspension bar inside a sealed casing that also contains the control unit for dosing the AdBlue. Ducts are in stainless steel or plastic insensitive to the oxidising effect of AdBlue. They are
heated by engine water (between the tank and pump) and an electric coil (between the pump and dosing module located along the chassis). The dosing module, which is fed with compressed air and AdBlue, is connected to an injector located on the exhaust pipe. The entire AdBlue storage, dosing and injection system has been subjected to testing in extreme climate conditions, both in Scandinavia
and Spain, to ensure system reliability complies with European regulations. The quantity of AdBlue to be injected is calculated by a control unit (dosage unit) that receives various types of input, for instance, the temperature of exhaust gases in the catalytic converter, quantity of
fuel injected in the engine, flow of aspirated air and environmental conditions. The catalytic converter,
together with the silencer, is located underneath the battery casing and comprises ceramic elements containing rare metals. The temperature in proximity to the catalytic converter is measured by two probes, one at the intake and one at the outlet of the silencer, to check atomisation of the AdBlue.
The catalytic converter/silencer casing is insulated to protect adjacent components from high temperatures.
Control of SCR system operation
Current regulations (EEC 88/77-EC1999/96-EC 2001/27) allow registration of Euro 3 vehicles and also those with Euro 4 or Euro 5 emission levels, however, they don't establish any other constraints
for the emission control system.
The European Commission therefore focused on the problem of emission control system efficiency and effectiveness over time. It then prepared the Directive concerning Euro 4 emissions, due for publication halfway through 2005. The Euro 4 Directive not only establishes emission levels, it also defines the characteristics of the emission control system, independent of the technology adopted.
Euro 4 vehicles coming into service after October 1, 2006 (October 1, 2005 for new type approvals) will have to be fitted with a diagnostics system (On Board Diagnostics) covering operation of the emission reduction system. So in the case of SCR a telltale will have to light up when the AdBlue level drops below a certain value (minimum 10% of the tank capacity). An 'irregular engine operation' telltale will light up when the tank is empty. Iveco Stralis Euro 4 models offered this year will already be fitted ahead of time with both these telltales and an AdBlue level gauge, which can be consulted using the OBD menu on the instrument panel display. The OBD is already able to identify and store details of system malfunctions.
One year after introduction of phase one – from October 1, 2007 for new registrations (starting October 1, 2006 for new type approvals) – all Euro 4 vehicles must be equipped with a system 'encouraging conformity with the law', again, independent of the technology adopted. If the nitrogen oxide content exceeds the maximum permissible value by a certain measure the warning 'irregular engine operation' will appear on the instrument panel and this anomaly will be recorded by the onboard computer. If the pre-alarm level is continuously exceeded (or for SCR vehicles, if the tank is empty) this will initiate a procedure governed by the electronic fuel injection management system to reduce engine torque. This reduction will take place after the vehicle's ignition is next turned off.
Again in accordance with the new Euro 4 regulations, the manufacturer must ensure that N3>16t category vehicles comply with polluting emission levels for 500,000 km or 7 years (N3<16t, 250,000
km - 6 years).
Governments in the various European countries will have to introduce a control procedure to be carried out by authorised operators who will check the on-board computer's memory to ensure the engine has always operated in conformity with Euro 4 regulations.
