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Continental showcases “Super Clean Electrified” connected, optimized 48V mild hybrid diesel; post-Eu6d

At the 38th International Vienna Motor Symposium this week, Continental is showcasing a 48-volt hybrid diesel vehicle which meets very stringent RDE (real driving emissions) limits on CO2 and NOx. The Continental Super-Clean Electrified Diesel combines electrification-based engine optimization and an electrically heated catalyst integrated in the exhaust aftertreatment system to achieve a 60% reduction in real-world NONOxx emissions and a simultaneous 2% reduction in CO2 emissions measured against the baseline Euro 6b vehicle.

The first 48-volt diesel hybrid has already gone into production in Europe, and a second production launch is already in the pipeline for 2017.

Img_2017_04_25_emobility_1_en-data

The Continental engineers implemented the clean diesel in several stages. They began by replacing the standard injection system with Continental’s PCRs5 piezo common rail injection system. This operates with maximum injection pressures of 2,500 bar. With the help of highly dynamic valve timing it is possible to perform multiple, very closely spaced and very precisely metered injections per cycle.

In this way a minute amount of fuel can be injected into the cylinder after the combustion event. This fuel is ignited only when it reaches the catalyst, thereby accelerating catalyst warm-up. This has important implications because the SCR catalyst has to reach a certain minimum operating temperature before it can begin converting nitrogen oxide emissions.

Tests show that this single measure—post-injection—can cut the SCR catalyst light-off time by around eight minutes, resulting in a reduction in cumulative nitrogen oxide emissions under the future WLTP (Worldwide harmonized Light-duty Test Procedure) driving cycle of 37%.

However, using only post-injection would increase fuel consumption by around 4%. Enter the 48-volt hybrid system based on a belt-driven starter-alternator. The electric motor, with a rated output of around 15 kW, not only allows braking energy to be recuperated and stored as electricity in a small lithium-ion battery but can also assist the internal combustion engine during short, sharp bursts of acceleration.

Img_2017_04_25_diesel_4_en-data
48 volt electric machine with integrated inverter. Click to enlarge.

This reduces the peaks in nitrogen oxide emissions under very sudden, heavy throttle application. By cutting the relative proportion of accelerating power that has to be supplied by the combustion engine—“phlegmatization”—the 48-volt system can reduce NOx by a further 3% over and above the reduction achieved by post-injection. At the same time CO2 emissions are cut back by an additional 3% approximately.

A further reduction in emissions is achieved by the use of a close-coupled electrically heated catalyst (EMICAT). Irrespective of the engine operating strategy,the heated catalyst, with a transient power rating of 3 kW, quickly brings the downstream-mounted SCR catalyst up to operating temperature, allowing it to start converting nitrogen oxides.

Img_2017_04_25_diesel_2_en-data
A fuel saving electric heatable catalytic converter on 48V basis. Click to enlarge.

The aqueous urea solution (AdBlue) used for SCR catalysis is injected into the exhaust stream immediately downstream of the heated catalyst. This arrangement guarantees good mixing of the exhaust gas and the urea, so that it is not necessary to fit a separate mixer. The heated catalyst reduces nitrogen oxide emissions by a further 14%. Fuel consumption is unaffected, since the electrical energy used for heating purposes is supplied entirely from braking energy recuperated by the 48-volt system.

An additional significant reduction in emissions is achieved with the help of connected Energy Management (cEM). The Super Clean Electrified Diesel presented in Vienna uses a cEM Traffic Light Assist (TLA) function to achieve a further reduction of nitrogen oxide emissions as well as a reduction in fuel consumption. The TLA predicts when the next traffic light—which may not yet actually be visible to the driver—will be on red and can then use this additional information to improve coasting, recuperation and braking management.

The beauty of ‘connected Energy Management’ is that we can implement a more energy-efficient driving strategy simply by using an improved database. 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.

—Dr. Oliver Maiwald, Head of Technology & Innovation with Continental’s Powertrain Division

In total, the measures featured on the test vehicle presented in the lecture in Vienna deliver a very significant 60% reduction in NOx, while at the same time achieving slight 2% drop in fuel consumption compared to a Euro 6 Diesel standard car.

In other words we have resolved a classic conflict of objectives in diesel engine development, showing that a clean diesel engine with emissions well within the legal limits doesn’t have to consume more fuel.

—José Avila, President of the Powertrain Division and Member of the Executive Board of Continental

Resources

  • Auerbach, M., Ruf, M., Bargende, M., Reuss, H. et al. (2011) “Potentials of Phlegmatization in Diesel Hybrid Electric Vehicles,” SAE Technical Paper 2011-37-0018 doi: 10.4271/2011-37-0018

Comments

SJC

A smaller diesel engine can do will on highway mileage while hybrid does well in city. Now they have to combine the two at the right price.

Peter_XX

You need bigger electric machines if you want to cut one cylinder but of course, it is possible. That option might just come with a somewhat bigger price tag; despite reduced number of cylinders (electric systems and batteries are so darn expensive). Eventually, the concept shown here should be very cost-effective, so we might see something similar in production pretty soon. The synergy with NOx reduction is compelling but Euro 6d can, of course, be met with conventional means (you can already buy such cars).

A full hybrid with diesel engine would cost more and thus, the total incremental price might be prohibitively high, in spite of lower fuel consumption than the gasoline counterpart.

mahonj

I wonder how many lines of code it took to do that ...

The "coasting on approach to red lights" function is a good idea and could be used for all engine types. All cars could switch the engine off, and electrics could use regenerative braking to recycle the energy. However, it would want to work well or it would be very annoying. + it wouldn't work well for people who see red lights as "guidelines"* rather than actual rules.

*in the words of Captain Barbossa from "Pirates of the Caribbean".

Juan Valdez

This is a failed attempt to solve a problem by increasing it's complexity. I think diesels are just too dirty to cost-effectively compete. Multiple reports said the VW diesel exhaust and treatment systems cost more than the engine.

Once you factor in all the costs of the 48v system, multiple exhaust treatments, and other technologies, is it really going to "win" over newer purely electric and hybrid systems, especially when you factor in 20 years of maintenance??

This is dead technology getting a short-lived second wind - I'd put all my R&D into electrification.

Peter_XX

@Juan
EV sales has already stagnated in the EU. They are far more expensive than diesel cars. These are the facts.

Darius

Peter XX

Diesel fuel cost is higher vs electricity at least 3 fold as well and smog within towns is anoying.

mahonj

It would be nice to get all the diesel cars and trucks out of cities, due to the local pollution (NOx, particualtes and soot).

However, this is unlikely to happen any time soon, as EVs are so expensive to buy and range limited. IMO, hybrids, such as this, which could be petrol (or Hydraulic) hybrids are a good idea.

Ideally, all stop-start deliveries could be electric or hybrid.

Where I live (Dublin) you can see row after row of (70% diesel) cars sitting in traffic, their engines running. If they even had mild hybridisation, their engines could be off for all the stationary (and maybe low speed) times, which would greatly improve air quality.

yoatmon

@ peter XX
I beg to differ. In their true physical nature, the real cost of EVs is far lower than ICEs.
The high prices are the result of small series production; mass production would lower an EV price below that of an ICE.
Manufacturers of ICEs are used to a certain margin of profit which they can not achieve with a low priced EV. To reach that margin, the effective price is simply increased respectively.

Carl

@mahonj,

According to European Environmental Agency's air quality assessment report (Air quality in Europe — 2016 report, EEA Report No 28/2016), Ireland has very CLEAN air generally, really the cleanest in Europe based on overall criteria pollutant monitoring data. It appears that there are only two monitors in Ireland in that monitoring system, but one of them appears to be in Dublin.

According to that report, ambient levels of all criteria pollutants, including NO2 and PM10/PM2.5 are all far below EU's ambient air quality standards, and even well below WHO air quality guidelines. I can tell you as as air pollution meteorologist that most metropolitan areas in the U.S. would be ecstatic with those air quality data!

Is EEA embellishing its accomplishments with respect to air quality there?

mahonj

@Carl, wow, that is some report. I had no idea we were so good; however, it smells very "diesely" in the city of Dublin outside my door at 8.30 in the mornings.

> Air quality in Europe — 2016 report, EEA Report No 28/2016
> I would doubt it, why would they, they are trying to get a picture of the EU.

However, my hybridisation wish still stands, except it would be more urgent in cities other than Dublin.

Carl

@mahonj,

Thank you for your response.

I assumed that the EEA report was valid, but it's so inconsistent with what I've been hearing about air quality in urban locations in Europe, something has to be hyped, one way or the other. It almost sounds in some articles like the air is barely breathable in many city, almost as bad as Beijing, China!

Again, if those EEA data are representative of the current air quality in Europe, they are actually much cleaner than most U.S. cities, especially with respect to ground-level ozone (an especially perplexing air quality problem in the U.S.)

I don't disagree about start/stop systems which are consistent with some degree of hybridization. It should be noted though that petrol engines have high PN emissions at each start-up, cold or hot.

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