German automotive giant Continental is bucking the general perception that diesel-powered cars’ days are numbered and declares that “diesel has a future”.
That bold statement comes on the back off Continental unveiling a new technology called Super Clean Electrified Diesel, which the company claims can reduce NOX emissions by 60 per cent.
The German tech and tyre company showcased the technology to assembled media, including CarAdvice, at its Continental tech Show 2017 in Hannover, Germany last week.
“The diesel engine will continue to play an important role in meeting mobility needs for the foreseeable future,” said José Avila, President of the Powertrain Division and member of the Executive Board of Continental, “so it is vital for us to develop the technology to support extremely low-pollutant diesel operation.”
In order to meet ever more stringent emissions standards in Europe, Continental’s engineers started by replacing a car’s standard injection system with its own Continental PCRs5 piezo common-rail injection system. Working under extreme pressure of 2500 bar and in conjunction with highly dynamic valve timing, the system performs multiple and very closely spaced metered injections of fuel per cycle. This allows for only the minutest amount of fuel to be injected into the cylinder after combustion and this fuel is only ignited after it reaches the catalyst, thus rapidly accelerating the vital catalyst warm-up function.
This is crucial to reducing emissions as the SCR catalyst has to reach a minimum operating temperature before it can start converting nitrous oxide emissions. Continental’s testing has shown this simple measure has reduced the warm-up time by around eight minutes which equates to a reduction in NOX emissions of around 37 per cent.
Above: The Continental 48-volt Belt Starter Generator
However, the system does not work in isolation, and in fact, if used in isolation it would see an increase of fuel consumption of around four per cent. To combat this, Continental has also developed a world-first 48-volt mild hybrid system. Based on a belt-driven starter/alternator, the mild hybrid not only recuperates energy from braking (which is stored in in a small lithium-ion battery) but then uses that stored energy to help the car under acceleration. This is typically, when NOX emissions are at their peak in a conventional diesel. The combined effect of the 48-volt mild hybrid system is a further reduction in NOX emissions of around three per cent while CO2 emissions are also reduced by three per cent.
A further 14 per cent reduction in NOX emissions is achieved via an electrically heated catalyst, dubbed EMICAT. The heated catalyst serves to quickly heat the SCR catalyst to optimal operating temperature, allowing the system to start converting nitrogen oxide sooner than in a conventional system. The power needed to heat the EMICAT is sourced exclusively from the stored energy harnessed by the 48-volt mild hybrid system.
Above: Continental’s electrically heated catalyst, EMICAT
Finally, Continental’s connected Energy Management (cEM) system helps the car operate at optimum efficiency by sending at receiving live data about traffic conditions.
“The beauty of ‘connected Energy Management’ is, that we can implement a more energy-efficient driving strategy simply by using an improved database,” said Dr. Oliver Maiwald, Head of Technology & Innovation with Continental’s Powertrain Division.
“When the cEM control unit is aware of the upcoming route (thanks to the navigation system or learning algorithms), it can decide in advance when the vehicle should coast and when it is best for it to recuperate braking energy, thereby saving fuel and emissions.”
The cEM also features a Traffic Light Assists (TLA) function which can predict when the next traffic light, whether visible to the driver or not, will be red. The cEM then uses this information to improve coasting, energy recuperation and braking management.
Above: connected Energy Management can alter driving dynamics based on live data updates
In total, Continental’s Super Clean Electrified Diesel system reduces NOX by 60 per cent while also achieving a four per cent reduction in fuel consumption.
“In other words we have resolved a classic conflict of objectives in diesel engine development,” said Avila, “showing that a clean diesel engine with emissions well within the legal limits doesn’t have to consume more fuel.”
CarAdvice spent some time behind the wheel of Continental’s test vehicle at the company’s Contidrom proving ground just outside Hannover.
The vehicle, somewhat ironically, a Volkswagen Golf, was fitted with all the systems outlined above as well as real-world emissions measuring system and it did indeed return NOX figures well below the current Euro 6 Diesel standard, prompting engineer Johannes Dreschel to boldly declare, “Continental believes in the diesel and we say ‘the diesel is not dead’.”
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