Scania unveils Euro 6 heavy-duty engines

Scania Euro 6 engine and aftertreatment system. Click to enlarge.

Scania is unveiling 440 and 480 hp (324 and 353 kW) 13-liter Euro 6-compliant engines. The engines combine a range of technical solutions to meet the more stringent emission requirements, while the consumption of fuel is as good as Scania’s Euro 5 engines.

In the development of the Euro 6 engines, all done in-house, Scania has combined all the new technologies developed by the company in recent years: exhaust gas recirculation; variable turbo geometry; common-rail high-pressure fuel injection; selective catalytic reduction; particulate filtering; and its own engine and exhaust management technology, now integrated into one system. The development of the new engine generation and technology has taken five years and cost approximately SEK 10 billion (US$1.6 billion).

Comparison of emission standards. Click to enlarge.

Euro 6. Euro 6 standards are being introduced 31 December 2013; emissions of nitrogen oxides and particulates are cut by around 80% compared with the standards currently in force (Euro 5). A new element in emission testing is that the particles also need to be counted, which in practice means that the actual particulate emissions will be around one-sixth of Euro 5.

Euro 6 is the first step towards the implementation of world harmonized emission standards, encompassing Europe, North America and Japan, and this will facilitate coordination and development for future standards. The Euro 6 levels are close to those applying in North America (EPA10) and Japan (Post NLT) starting in 2010. Euro 6 is the first time the new WHDC (world harmonized duty cycle) is stipulated for certification.

The following emission levels apply:

• Nitrogen oxides: 0.4 g/kWh (2 g/kWh for Euro 5)
• Particulate matter: 0.01 g/kWh (0.02/0.03 depending on test cycle for Euro 5)
• Particulate count: 6.00 x 10¹¹ particles/kWh (transient test cycle). 8.00 x 10¹¹ particles/kWh (stationary test cycle). This amounts to 600 or 800 billion particles per kWh. One kWh corresponds to the energy consumed during approx. 30 s of driving for a 40-tonne combination at highway speed. There is no counting requirement for Euro 5, but the reduction in the number of particulates is likely to be around 99%.

Euro 6 truck range: 440 and 480 hp. The 440 and 480 hp engines will be available across the G- and R-series ranges for all types of applications, including ADR transport. Multi-wheelers (8×2 and 8×4) will follow during 2012.

Performance is very similar to the Euro 5 EGR engines on which they are based, hence the torque-to-power ratio is around 5.2—the highest in the industry, according to Scania.
As on Scania’s other Euro 5 engines, full torque is available from 1,000 rpm. Transmissions include 12+2-speed range-splitter gearboxes with or without overdrive. Scania Opticruise is recommended to ensure maximum fuel efficiency and to facilitate gearchanging (also available with clutch pedal). Manual gearchanging can be specified. Scania Retarder is an option in all combinations.

The consumption of AdBlue for emission aftertreatment corresponds to 3-4% of the fuel consumption, compared to 5-6% for Scania’s Euro 5 SCR engines.

Scania Euro 6 engines are currently approved for running on typical mixes of up to 8% approved biodiesel in normal diesel. Tests are ongoing to secure the long-term functioning of the aftertreatment system when running on up to 100% biodiesel.

Basic engine. The new 440 and 480 hp engines are based on Scania’s latest modular engine platform with 130 mm cylinder bore introduced as Euro 5 with EGR in 2007. These engines feature common-rail fuel injection (Scania XPI), EGR and variable-geometry turbocharging (VGT). The first V8 engine on this platform (730 hp, 3500 N&iddot;m) was launched in 2010, also equipped with Scania XPI and VGT, but with SCR exhaust aftertreatment like the other Euro 5 V8 engines.

Scania’s own engine management system is used on the entire range. The fully modular design means that many parts and components are shared across the range, which facilitates servicing and promotes parts availability.

The cast-iron cylinder block is unchanged, being designed from the outset for high combustion pressures (in this case up to 200 bar). As on Scania’s other 13-litre engines, a ladder frame between the block and the sump is used to stabilize the lower part of the engine and counteract noise and vibration. Low-friction plasma-coated cylinder liners are used to reduce fuel consumption. Steel pistons are used with a slightly reshaped bowl giving a 17.3:1 compression ratio.

Low-emitting open crankcase ventilation is standard and the new plastic oil sump increases oil capacity by 3 liters, while reducing noise and saving weight. The weight of the engine itself is similar to Euro 5 EGR. Overall vehicle weight is up by up to 200 kg due to the AdBlue system (75-liter tank) and the added complexity of the exhaust system.

Cooling capacity was upgraded for the needs of Euro 6 in conjunction with the launch of the new R-series in 2009. A smart cooling fan is used that interacts with the engine management system to save fuel and to optimize retarder performance. A high-speed cooling fan can be specified for exceptional conditions.

Engine management, including full aftertreatment control. The new Scania Engine Management system (same as on the 16.4-liter V8) controls all engine parameters as well as the exhaust aftertreatment system and with full integration with other systems on the vehicle. A novel solution with sensors in the silencer enables precise control of exhaust temperature and NO_x levels.

Injection system. The Scania XPI (extra high pressure injection) common-rail fuel injection system is designed for injection pressures of up to 2,400 bar, with typically around 1,800 bar in normal operation. The eight-hole injectors provide up to three injection pulses per cycle to achieve optimum engine and emission performance. When needed, post injection is used to maintain the optimum exhaust temperature.

Intake air handling. Scania VGT (variable-geometry turbocharging) is combined with Scania EGR (exhaust gas recirculation) with single-stage cooling. VGT significantly boosts driveability and engine response and is also beneficial for the gearchanging speed with Scania Opticruise. EGR rates are somewhat lower than for Euro 5 (up to 25% vs. 30%) since the EGR and SCR systems can be balanced for optimum performance.

An intake air throttle with position sensor is used to finely control intake airflow. Restricting the flow through the engine when it is not pulling helps keeping up the temperature in the exhaust system to achieve maximum efficiency in the SCR system.

Exhaust aftertreatment. The integrated silencer is a compact insulated unit containing an oxidation catalyst and a full-flow particulate filter, followed by two parallel SCR catalysts and ammonium slip catalysts.

Scania has developed a new electrically actuated AdBlue dosage system for higher precision, greater robustness and airless operation. AdBlue is injected into a mixer (patented by Scania) and evaporates into urea before entering the two parallel SCR catalysts.

Next in line is a compact and efficient ammonium-slip catalyst to remove any ammonium left in the exhaust flow. The evaporation route is extremely short, making it easy to maintain the required temperature. The system is monitored by new temperature, pressure and NO_x sensors.

The EGR and SCR processes are continuously balanced to optimize emission performance. Typically, around 50% of NO_x emissions are eliminated at source by the EGR system and another 95% in the SCR catalysts and the particulate filter reduces particulate emissions by 99%.

Click to enlarge.

Integrated particulate filter. Via two sensors, the pressure differential is monitored across the integrated particulate filter to assess the degree of contamination and, hence, the need for regeneration. Regeneration takes place continuously during driving. If the filter still starts to clog with soot, the driver will get recommendations in the central instrument. A switch is provided in case a stationary regeneration cycle should be required.

The particulate filter needs to be cleaned at regular intervals. It is detachable from the silencer unit, which is mounted on a swing-out attachment with two bolts for easy maintenance and replacement of the filter cartridge.