Engine development is becoming ever more demanding. Dr Christian Weiskirch, Head of Performance and Emissions, Heavy-Duty Inline Engines at MAN Truck & Bus, talks about the next level of Euro 6, new statutory requirements, as well as innovative technology to further increase customer satisfaction.
The Euro 6c stage further tightens the threshold values for on-board diagnosis (OBD). This means a further decrease in nitrogen emissions under real driving conditions. As a result, we had to make extensive adjustments to the engine as well as the exhaust gas after-treatment system.
We definitely had a tight schedule. Key development phases had to be implemented within two years. In fact, we just completed the last fine-tuning during this summer’s testing period. The project’s overall duration amounted to three years.
Right from the outset, the extensive adaptations were associated with a tremendous amount of complexity to ensure the technology functioned and performed properly when used by our customers. To make this happen, development and production teams had to work in a closely coordinated manner. Ultimately, we had to be able to implement the measures on a series-scale as well. Due to the tight timeline, coordination with procurement and quality assurance departments was also a critical aspect so that we could source the required parts and components of the proper quality from the respective suppliers at the right time. This is where the core team run by project manager Thorsten Oberpenning did a great job. I also want to highlight the excellent collaboration with the vehicle integration project, which incorporates newly developed engines into a vehicle.
First of all, compliance with the statutory requirements was obviously paramount. By using a new SCR catalytic converter to reduce nitrogen oxides in the exhaust gases combined with a customized engine operating strategy, we were able to consistently meet this specification. Production had to deal with the complexity of implementing corrosion-resistant bearings. The bearings are resistant to oleic acids, but are more vulnerable to grime associated with the residue from production and machining processes. For that reason, we had to modify the production process accordingly and thereby meet the related higher specifications. Given the tight schedule, developing other new components, such as steel pistons, exhaust gas turbochargers, and the engine speed-controlled coolant pump, were downright individual accomplishments.
The most significant innovation for customers could be potential fuel savings of up to 2.5%, despite tighter emissions control specifications. At the same time, the maximum power was increased by 20 hp, and the maximum torque of 2,500 Nm is now available in all gears. Combined with optimizing measures in terms of aerodynamics, the transmission, and assistance systems, it all results in improved fuel consumption by a respectable 4.2% to 9.6%. Simultaneously, we raised the oil change intervals to 140,000 kilometres and diesel particle filter maintenance to 850,000 kilometres. Overall, customers will benefit from a nicely enhanced package.
As already mentioned, the corrosion-resistant bearings require a fully customized assembly process until the crankcase is closed so as to prevent contamination. From now on, that process takes place in an environment in which airborne particles are regulated and monitored – namely in clean-room conditions. The new components naturally also resulted in changes to the individual assembly steps, such as installing the engine cable harness. Ultimately, the modifications affect all process steps, up to and including the quality assurance measures at the end of the assembly line, where cold- and hot-testing runs were re-calibrated. By getting the pre-series production centre on board early on, we were able to run all prototype engines through the serial production line. That measure represents a valuable economy of time and a head start in terms of reliable process stability.
The competition never rests and will continue to optimize the fuel consumption of engines to offer customers the best-possible total cost of ownership (TCO) for their vehicles. There will be a cost-benefit analysis in regard to what measures are worthwhile in terms of development and what the timeframe should be. Engine-related steps to further improve fuel consumption are becoming smaller and also more cost-intensive. Nevertheless, lawmakers are putting more pressure on the manufacturers with the CO2 declaration that will become mandatory as of 2018. The Euro 6d standard is scheduled to take effect in the fall of 2019, with truck tolls to be based on CO2 emissions starting in 2021.
We will keep working on offering customers highly robust engines that have the best-possible fuel consumption. We look forward to taking on this challenge – not least because we have the knowledge, experience, and passion to find the right solutions.
Images © Florian Generotzky