7 June 2005
Scania has unveiled its Euro IV/V bus engines, relying on cooled exhaust gas recirculation (EGR)—rather than the urea-SCR technology—for NOx control. “Scania strives to make things simple and efficient for operators. No extra substances need to be handled and no extra installations are required on a Scania bus,” said Hasse Johansson, head of research and development at Scania.
Scania has decided on a long-term strategy to use cooled EGR on buses to reduce emissions for Euro IV as well as Euro V. “EGR is a tried-and-proven technology that is used on diesel engines worldwide today. Environmental performance is secured in all operating conditions, including stop-go city and suburban traffic,” said Johansson. Scania has sold over 2,000 Euro IV trucks with EGR to customers in Europe.
In the Scania EGR, a part of the exhaust flow—up to 18% for Euro IV and 25% for Euro V—is taken out before the turbocharger and is cooled by the engine coolant before blending with the intake air. A valve system is used to regulate the flow in relation to engine load. To feed the exhaust gases into the intake air, which has a higher pressure, Scania uses a venturi system installed in the intake manifold.
PM emissions are controlled through the use of high-pressure fuel injection in combination with a diesel oxidation catalyst. Operators that wish to reduce PM emissions beyond legal limits will be able to specify an optional PM reduction device (standard on Euro V engines), called by Scania a “maintenance-free particulate filter”. The PM reducing device is a “part-flow” filter design, capable of reducing PM emissions by about 50% without the risk of clogging, said Scania. The device is integrated in the normal silencer. (A PM control device of similar performance that was introduced under the trade name PM-Kat on Euro IV engines by MAN utilizes a “partial flow” substrate by Emitec.)
Scania’s city bus engines for Euro IV and Euro V are all based on a 9 liter 5-cylinder unit derived from Scania’s modular engine platform. Power ratings are 230, 270 and 310 hp, with torque of 1,050, 1,250 and 1,550 Nm, respectively. Initially, the Euro V engine will be rated at 270 hp.
Scania’s bus engines for Euro IV are available from November 2005. Euro V engines and the particulate control devices are scheduled to become available during 2006.
Source: Scania (press release)