At the 27th Aachen Colloquium, Continental exhibited how 48V hybrid technology can be used to deliver reduced nitrogen oxide (NOx) emissions for both diesel and gasoline engines.
Continental’s approach combines engine-integrated technology packages with electrically assisted exhaust aftertreatment functions. These new functions, powered by the additional electrical energy generated by a 48V hybrid vehicle, open the way for further advances in both emissions and fuel consumption.
For the beleaguered diesel engine, for example, such measures are more urgent than ever before. A Continental demonstration, performed under real-world driving conditions, shows that it can: The NOx emissions of the second-generation “Super Clean Electrified Diesel” remained consistently below 35 mg/km NOx across the entire test cycle, including urban cold-start driving.
“Using the Continental technology packages, it is possible to combine reduced emissions with even more frugal fuel consumption. Equipped with 48V hybridisation, diesel engines are able to combine their fuel efficiency with NOx emissions so low they even comply with the NOx limits currently under discussion for the next, even tougher stage in EU emissions legislation. That means the fuel-efficient diesel engine will be able to continue making a contribution to reduced CO2 emissions,” says Wolfgang Breuer, head of the Engine Systems business unit at Continental.
Can a C-segment diesel car with Euro 6b type approval be adapted to meet the requirements currently under discussion for the upcoming Euro 7 standard? Taking its Super Clean Electrified Diesel technology, first presented in 2016, as an example, Continental has confirmed that it can. The solutions designed to enable compliance at realistic cost with requirements stricter than those of the future Euro 6d standard, include two SCR catalysts and an EMICAT electrically heated catalyst.
“We set ourselves the target of reducing real-world NOx emissions to less than 35 mg/km, while at the same time also cutting fuel consumption,” says Giovanni Avolio, head of Diesel System Engineering at the Engine Systems business unit. Both goals were met: NOx emissions were reduced to less than 35 mg/km, while CO2 emissions were also reduced by up to 10 g/km.
With the hardware packages and new control functions, Continental has met a number of important development goals, allowing the performance of the electric motor to be optimised both in driving mode and recuperation mode, while the electrically heated catalyst EMICAT enables the engine management to achieve consistently low-CO2 operation sooner. At the same time, the charge status of the 48V battery is managed so that the battery has as much charge in reserve at the end of the journey as when setting out.
One requirement shared by diesel and gasoline engines is that a sufficiently high exhaust system temperature must be maintained across all load conditions if the aftertreatment system is to deliver high conversion efficiency at all times. With this in mind Continental has now developed a catalytic converter for gasoline-powered vehicles featuring two integrated electrically heated discs.
“Due to the positioning of these two heated discs (Dual Electrical Heatable Catalyst), it takes only a few seconds for the entire catalytic converter to reach an efficient conversion temperature,” says Thomas Knorr, Group Leader Technology & Innovation at the Powertrain division. The aim of this technology is to help ensure compliance with strict NOx emission standards for gasoline engines.
Another thing that direct-injection gasoline vehicles and diesels increasingly have in common is that more and more gasoline vehicles are now being equipped with a particulate filter (gasoline particulate filter, GPF). As soon as the particulate load in the GPF reaches a given level, the filter must be regenerated. Here too the new technology from Continental can help: “By appropriate control of the two heated discs in the catalytic converter, we can ensure that the second disc also generates the required temperature for regeneration of the downstream GPF by purely electric means,” says Knorr.