10 September 2007

As the first heavy vehicle manufacturer, Scania introduced Euro V engines utilizing exhaust gas recirculation (EGR) and no exhaust gas aftertreatment. The Euro V EGR engine line up includes 5 and 6 cylinder (9 and 13 liter) inline engines. The new engines will gradually replace the current platform over the next few years, said Scania. The only engine that is not available in the EGR version is the largest, 16 liter V8 unit.

For several years, Scania has been offering Euro IV engines with EGR. However, due to such issues as heat dissipation from EGR cooling, urea-SCR has been used in larger Euro IV units (16 liter), as well as in Scania Euro V engines (16 and 12 liter). Plans to launch Euro V EGR engines were announced by Scania in December 2006.

The new 230 and 280 hp (as well as a 270 hp ethanol version) 5 cylinder engines meet the voluntary EEV (enhanced environmentally friendly vehicle) emission standards, which are identical to Euro V, with the exception of a more stringent HC limit. The 230 and 280 hp engines are fitted with a flow-through (“part-flow”) filter to control PM emissions.

The largest of the new 5 cylinder engines (320 hp) and the new 6 cylinder engines (360, 400, 440, and 480 hp) meet Euro V emissions with no exhaust aftertreatment of any kind. The higher output engines feature two-stage EGR cooling.

In terms of fuel economy, the new engines match the existing range of Euro III and Euro IV engines, said Scania. All engines give maximum torque from 1000 rpm for extra low-speed power and driveability. Maximum torque extends to 1350 rpm (230 hp: 1000-1500 rpm) for 9 liter and to 1300 rpm for 13 liter engines. Oil change intervals have been extended to 120,000/90,000 km at max. 36/45 tonnes gross vehicle weight.

Particulate emissions are controlled mainly through the Scania XPI common rail injection system, which has been developed jointly with Cummins. The operating pressure ranges from an idling pressure of around 500 bar to a peak pressure of 2400 bar. The average working pressure is around 1800 bar. A pilot injection is used to reduce noise, and a post-injection to reduce soot and NOx emissions.

Scania EGR has been revised to provide higher efficiency and capacity. The amount of EGR is controlled electronically via an EGR valve and by varying the geometry of the turbocharger, thus varying the exhaust backpressure. Recirculated exhaust gases are supplied from the exhaust manifold and cooled in a water-cooled EGR-cooler. On high output engines, two-stage EGR-cooling is employed. 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.

The engines utilize a variable-geometry turbocharger (VGT). The VGT geometry and gas flow are regulated by a sliding nozzle-ring, which is controlled by an electric actuator. This allows precise control of both charge-air to the engine and the flow of EGR.

Biodiesel blends can be used in the new engines, including neat biodiesel (B100). With blends above 5% biodiesel (B5), oil change intervals are halved. When B100 is used, the power output is reduced by 17%, and NOx increases by 17%.

Source: Scania