Questioning the Electric Vehicle Orthodoxy.
I know what you're thinking: "A powertrain story? Really? Everything is going electric, so why bother? The internal combustion engine (ICE) is all but dead." Judging from the increasing number of column inches devoted to breathlessly promoting electric vehicles (EVs), a case could be made for writing off the ICE and preparing for the inevitable switch to electrification, one that starts with a wholesale move to plug-in hybrids (PHEVs) and is followed by a swift ramp-up to pure EVs. From there, ICEs are dead and buried, never to return. The end.
"If only it was that easy," says J.D. Kehoe, Mahle North America's Director of Product Development, Filtration and Engine Peripherals (us.mahle.com). "It's a very dynamic time in the auto industry with different approaches from region to region that demand a blend of propulsion options that will be available for some time." Kehoe can see a future where China leads in the advancement of battery electric vehicles, Japan pushes hydrogen fuel cells, Europe--where city centers from London to Paris and beyond--moves from banning diesel power to banning gasoline-engined vehicles as well, while the U.S.--where gasoline is both plentiful and relatively cheap--will continue on a path that increasingly combines turbocharged, downsized ICEs with hybrid drive systems. Which is not to say that there won't be a level of cross pollination as EVs, fuel cells and ICEs mingle in the marketplace.
"The push toward EVs in China and Europe," says Kehoe, "is being driven by proposed legislation. The challenge in a global market is the acceptance of those technologies in other regions." For example diesel, which--with the help of legislation--until recently accounted for as much as 60 percent of Europe's passenger vehicle market, never really caught on in Asia or North America, and European automakers were forced to not only supply a greater proportion of gasoline-powered vehicles in these markets, but to create hybrid models they didn't sell at home. It's why, unlike VW and its MEB modular EV platform, BMW's two newest architectures, known internally as "FAAR" and "CLAR," will be "multi-fuel" platforms that will support ICE, PHEV and full electric powertrains. As BMW platform strategist Lutz Meyer recently told Britain's Autocar magazine, this strategy is essential due to the inability to predict "with any accuracy" the rate at which buyers will shift to EVs, and the need to meet the demands of individual markets.
This puts a lot of pressure on suppliers as they struggle to cover all the bases, especially as profitability in these new areas remains elusive. Over the past few years, Mahle purchased a controlling interest in Letrika, Kokusan Denki and Nagares, and combined them in a new Mechatronics division to handle everything from starters and alternators, to fuel injection systems and electric motors, to charging systems and motor controllers. This was done to keep pace with the changing automotive landscape. According to Kehoe, "The ICE side of the business is supporting our investment in electric drive systems until such time as consumer demand for electric vehicles makes this no longer necessary. Should that equation reverse, we will do the same to support our ICE research and development. As long as there is demand for either, we will be there to support it."
He says, however, that this uncertainty has brought with it another change, a more open dialog between OEM and supplier. "In the past," he says, "it used to be, 'This is what we need,' because most automakers knew what their boundary layer conditions were. They knew what they needed." Now, however, the statement has turned into a question: "What's possible?" Says Kehoe, "There's a lot more interest in getting ideas on the table, seeing how they fit into their systems, and determining what that means for the subsystems. Just 10 years ago we never heard a question we are hearing a lot now: 'Here's what we're thinking. Is this even possible?'"
The expectation is that powertrain technology will follow three paths: downsizing, hybridization and electric drive. Pure electric drive is a standalone, and one that is being driven by legislation, which has a major impact on customer acceptance. Conversely, continued downsizing and hybridization are not only increasingly common, the technologies are complementary. "There's a lot of cost balancing going on," says Kehoe, "in terms of what's possible, performance, market penetration and differentiation. There are a lot of choices, but--unlike in the past--not everyone is looking at the same page of the menu." Nor will they necessarily come up with the same solutions.
In 10 years, says Kehoe, there will be a mix of powertrains ranging from ICEs to pure electrics. The distribution of each, however, will depend upon the region, legislation, consumer acceptance, and--ultimately--cost. Even so, he imagines a situation similar to that seen in computers, where desktops and laptops have been overtaken by tablets and smartphones. "It may not happen to the same degree with powertrain," he admits, "but the range of options available to the consumer will certainly increase, making this one of the most exciting times in automotive history in terms of the potential for change."
RELATED ARTICLE: F1 Tech for the Road.
Continued engine downsizing will mean increased boost pressure and compression ratios, and require greater resistance to higher operating temperatures and mechanical loads. Mahle's 1.2-liter direct injection three-cylinder (DI-3) is one such engine. It combines a 48-volt electric supercharger and turbo to produce a massive 259 hp and 334 lb.-ft. of torque. Not surprisingly it is a bedplate design with through-bolt construction, Nikasil-coated cylinder bores and separate head and block cooling circuits. Fitting a 48-volt eSupercharger delivers high torque from low engine speeds and permits use of a larger conventional turbo to increase maximum output without introducing crippling turbo lag. There's also a 48-volt belt integrated starter generator for stop-start capability.
Waiting in the wings, however, is a technology that has revolutionized Formula 1. Turbulent Jet Ignition (TJI) is built into the cylinder head's spark plug well and includes a pre-chamber containing a low-flow direct injector and a small spark plug. This combination creates fast-moving jets of burned/burning fuel that is injected into the cylinder to ignite the much leaner air/fuel mixture in the cylinder. The secondary injector flows up to 3 percent of the total fuel energy through the orifices in the pre-injection nozzle, while the remaining 97 percent is introduced as a lean charge into the engine through port injectors. Mahle claims high combustion efficiency in the cylinder with very low soot and few, if any, rich pockets of fuel. This is because the fuel mixture in the cylinder is ignited from multiple points around its periphery at high speed.
Funded by the U.S. Department of Energy, the TJI system initially was installed on a light duty spark ignition engine for testing. It showed a thermal efficiency of 45 percent, a 30 percent improvement in fuel economy on the drive cycle, and 46 percent peak net thermal efficiency. Mahle has used CFD to study not only why the jet velocity is asymmetric, but how to mitigate it. However, its tie-up with the Ferrari F1 team has pushed development of the technology at a velocity close to that of the TJI's fuel mixture. Though official numbers are unavailable, the Formula 1 media speculate this technology has allowed Ferrari to increase engine power from 850 hp to nearly 1,000, all with greater fuel efficiency. Not bad for a 1.6-liter, V6 engine. Producing a boosted and downsized power unit for production (like the DI-3) and mating it to a hybrid drive system would not only further boost efficiency and reduce emissions, it would get an OEM most of the way to F1 tech for the road.
By CHRISTOPHER A. SAWYER, Contributing Editor
Caption: Turbulent Jet Ignition places a direct injector and spark plug together, using a dense initial charge to ignite a larger, leaner primary mixture introduced via port injection. The result is dramatically higher efficiency, lower emissions and more power. Mahle has continued to refine the concept, most significantly with the Ferrari F1 team.
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|Author:||Sawyer, Christopher A.|
|Publication:||Automotive Design & Production|
|Date:||Nov 1, 2018|
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