Between 1970 and 2000 Scania halved fuel consumption per tonne-kilometer for truck haulage. The company’s goal is to halve fuel consumption once again by 2020. Besides lower fuel consumption, common rail, turbocharged, inter-cooled diesel engines now popular in Europe do well in terms of most green house gases, The Scania XPI is an example of new, extra high-pressure injection systems that are being introduced.
Scania to Euro 5 without exhaust gas after treatment? This is a commendable achievement and speaks to the efficiency achieved with a number of new technologies. Current development includes improved EGR (Exhaust Gas Recirculation), which, according to a report from Green Car Congress, works in collaboration with a new fuel injection system:
The new engine platform is optimized for exhaust gas recirculation (EGR) and for Scania XPI, the new extra high-pressure injection system (peak pressure of 2,400 bar, average working pressure of around 1,800 bar) developed jointly with Cummins.
Multiple injections are possible with this electronically controlled injection system. A small amount of fuel (pilot injection) can be injected slightly before the main injection to reduce noise and prepare the combustion chamber for lower emissions. A small post-injection shortly after the main injection reduces soot and NOx. It can also be used to control exhaust temperature to suit some future aftertreatment systems.
Scania has co-operated with Cummins to develop injection and combustion technology since the early 1990s. Scania HPI, launched in 2001, was the first result of this long-term strategic alliance.
With proper design, high-output diesel engines, i.e., turbo-charged inter-cooled common rail, benefit from optimized EGR. Scania has developed two-stage EGR-cooling, some features of which have been patented. “The second stage consists of an air-cooled radiator mounted on top of the charge-cooler. A by-pass valve regulates the flow through the second EGR cooler.”
Scania revised its EGR to provide higher efficiency and capacity. A high-capacity water-cooled EGR-cooler is mounted on the engine. Recirculated exhaust gases are supplied from the exhaust manifold, cooled and passed on either to the intake side or to a second cooling stage. The amount of EGR admitted to the intake is regulated electronically via an EGR valve and by varying the geometry of
the turbocharger, thus varying the exhaust backpressure.Scania developed a new generation of engine management systems to control of all aspects of engine performance: fuel injection, dual-stage EGR, charge-air, cooling fan and engine operating temperature, variable-geometry turbo, exhaust braking, emission compliance (NOx control), exhaust aftertreatment and engine oil level.
The new engine management system also provides advanced on-board diagnostics that will be further developed over time and allows detailed logging of operational data for subsequent analysis. Together with the new Scania Communicator, logging can be done remotely via the Scania Fleet Management portal. Analyses can be performed on driver as well as vehicle data.
