Automotive News - January 7, 2008 - (Page 26b)

26B • JANUARY 7, 2008 Gasoline-diesel combo moves closer to reality Wim Oude Weernink woweernink@craincom.de Pros and cons Benefits of gasoline-diesel engine Better fuel economy than gasoline Lower manufacturing costs than diesel, slightly higher than gasoline Cleaner combustion Challenges to be overcome Hard-to-control combustion High CO, hydrocarbon emissions Still needs spark-ignition mode Heat and pressure problems Powertrain designers have long sought to combine the advantages of gasoline and diesel internal combustion engines into a single unit. Despite research that can be traced back almost to the birth of the auto industry, development costs and other technical barriers have frustrated developers. But increased pressure to improve fuel efficiency and the creation of better engine control technologies have caused several leading automakers to revive research in this area. Gasoline-powered engines using the spark-ignition process pioneered by August Otto and self-igniting engines invented by Rudolf Diesel each have distinct advantages. Gasoline engines emit fewer particulates and lower levels of nitrogen oxides than diesels because of their lower operating temperatures. Diesels are more fuel efficient than gasoline engines because of their higher operating temperatures. But diesels emit more nitrogen oxides and particulates because of the higher temperatures and incomplete combustion that come from the diesel’s process of compressing air to the point of igniting fuel. Spurred by pending legislation that requires reduced emissions of NOx and a proposal to cut CO2 emissions even further, researchers are seeking a so-called gasoline-diesel engine. Volkswagen’s prototype homogeneous charge compression engine combines the advantages of diesel and gasoline engines. Experimental process Volkswagen, Daimler and General Motors have just released details about what is now known as the homogeneous charge compression ignition, or HCCI, process. Other carmakers are working on similar engines. “But not all of them are currently prepared to come out with their activities,” said Philip Gott, Global Insight’s U.S.-based director of automotive consulting. “We are also working on it,” Masatami Takimoto, Toyota executive vice president of powertrain r&d, told Automotive News Europe. “We need to improve fuel efficiency, and combining the combustion methods of diesel and gasoline engines is one possible solution.” The HCCI process has to reconcile a glaring contradiction: Gasoline engines compress an air-fuel mixture to about 102 pounds of pressure per square inch before igniting it using a spark. But diesels compress air to about 319 psi, heating the air enough to instantly ignite fuel injected into it. An HCCI engine runs on gasoline but operates like both engines, in turn. When starting or at full load, it runs like a regular gasoline engine with spark ignition. But in its most efficient mode, the HCCI operates like a diesel. It doesn’t use a spark but compresses the air-fuel mixture to diesellike pressures to force self-ignition. Running at part load in diesel mode, the efficiency of the HCCI en- gine can be comparable to diesels — up to 15 percent more efficient than an indirect gasoline-injection spark engine, proponents say. Because of lower combustion temperatures, the use of up to 70 percent exhaust recirculation and homogeneous combustion of the air-fuel mixture, HCCI engines will not need expensive exhaust gas aftertreatment to meet future emissions rules. So an HCCI would cost only about $300 more to manufacture than a standard gasoline unit. “Adding a traditional three-way catalytic converter is enough,” said VW spokesman Christopher Kohnen. Controlling combustion But HCCI engines are not yet refined enough to market. When starting or accelerating under full load, the experimental engines still require spark plugs to operate smoothly. “Proper combustion control is our How HCCI engines work A homogeneous charge compression ignition engine is a gasoline engine without a traditional spark ignition to initiate combustion. Instead, the mixture of air and directly injected gasoline is compressed to such high pressure and temperature that ignition occurs simultaneously at several places in the cylinder. Because of lower combustion temperatures than in diesel engines — partly because of recirculating exhaust gases — NOx emissions from HCCI engines are low. The homogeneous combustion also reduces particulates. That means particulate filters and D-NOx catalytic converters are not needed. But carbon monoxide and hydrocarbon emissions are higher, requiring traditional three-way catalytic converters. Because of the self-ignition of the mixture, an HCCI engine requires advanced electronic logarithm engine mapping, combustion pressure sensors and variable valve timing to control the process. But with higher compression ratios, fuel efficiency is better than in ordinary gasoline engines. — Wim Oude Weernink biggest challenge,” Uwe Grebe, executive director of GM Powertrain advanced engineering, told Automotive News Europe. “The change from spark-ignition mode to self-ignition still needs a lot of development.” For GM, the self-ignition mode works well up to about 56 mph. Volkswagen says its self-ignition mode works from about 25 to 62 mph. Rough transitions from one mode to the other also are a problem. To speed the switches, researchers use advanced logarithm engine management systems and combustion pressure sensors. But the researchers say those switches need to improve. Test drivers “did not like the sudden change from a smooth gasoline engine sound to a rough diesel noise and vice versa,” Grebe said. Researchers have been working for five years to stabilize the combustion processes. Now they are focusing on variable working conditions. Variable valve timing, controlled injection timing and mixture temperature control are crucial parameters. “But atmospheric pressure and humidity also play a role,” Grebe said. Daimler even includes a variable compression ratio in its HCCI engine. It calls the engine DiesOtto. “We have added variable compression ratio with an adjustable crankshaft stroke,” a Daimler engine specialist said. “Because of that, we have all variables under control.” Different methods Each route to HCCI differs. Daimler presented a 1.8-liter, four- cylinder DiesOtto engine last July. With turbocharging, variable compression ratio and variable valve timing, it produces 238 hp. It was in the Mercedes F700 concept at September’s Frankfurt auto show. GM’s 180-hp HCCI engine is a modified 2.2-liter Ecotech. GM added special variable valve timing, valve lifters and an advanced combustion control management system. VW’s HCCI engine is based on an existing 1.6 FSI gasoline engine, adding modified variable valve timing and advanced engine management. Daimler said it needs a variable compression ratio to use normal gasoline. VW and GM say theirs run on gasoline or even E85. HCCI also can be based on existing gasoline engine architectures. Daimler says it will design future gasoline engines to handle HCCI applications. “The extra sensors and engine management may cost extra, but you will save on manufacturing costs because you do not need expensive exhaust gas after-treatment systems,” said Global Insight’s Gott. Daimler, VW and GM won’t say when they might offer HCCI engines. Industry sources expect it will take at least seven more years. “GM may bring this engine to the market in a mixed gasoline-diesel model by 2015,” Gott said. A Roland Berger study says volume production is not feasible until 2020. Industry sources say HCCI engines are ideal for hybrid cars that use internal combustion engines only to recharge the battery. HCCIs also could boost well-to-wheel energy efficiency. “If the U.S. shifts to diesel use on a large scale, that could upset the balance between gasoline and diesel fuel at the refinery level,” Gott said. “In effect, the HCCI is the long-term salvation of the internal combustion engine.” c Your future vehicle product plans represent billion-dollar investments. Are the opportunities you’re considering competitively positioned to optimize future margins market-by-market?… platform-by-platform? CSM White Space underexposed opportunities to ensure you don’t let billions of dollars and years of planning show up as red ink. 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Table of Contents Feed for the Digital Edition of Automotive News - January 7, 2008

Caddy V-8 is endangered species An industry turns green -- let's talk JAPAN TRIUMPHANT Ford, Microsoft to offer 911 service in Sync GPS will track fuel price Brose buys Siemens motor unit as step toward N.A. growth Expanding Meridian sees bright future Federal-Mogul CEO to stay Harbour Consulting sold Soft market threatens Tundra sales goal Ford dumps volume targets for dealer bonuses How HCCI engines work Visteon: 'We're leaner and smaller' Ford doubles regional promo money Gasoline-diesel combo moves closer to reality Rethinking retail: A hot topic at World Congress Denso expands hybrid plant CAFE fines may yield meager grants Some pay raise: To $8.3 million from $1 New Chrysler purchasing chief looks to Asia BMW adds jobs to boost S.C. output Continental layoffs follow production cuts at Chrysler Study: Indirect loan delinquencies soar No more peekaboo for Camaro Saturn's Lajdziak: GM is 'where I wanted to be' LETTER TO THE EDITOR Why buy Japanese? Here's an answer CAFE will put new entrees on auto show menu What an exciting way to start 2008 LETTER TO THE EDITOR 84-month financing is nothing new LETTER TO THE EDITOR GM ad policy shift is good for dealers JAMES B. TREECE Detroit show gets back on a global track LETTER TO THE EDITOR Too many dealers: Blame greed LETTER TO THE EDITOR Why not learn from Toyota? LETTER TO THE EDITOR A hot news item? Nah; it's 9 years old Suppliers to the 2008 Saturn Vue Supplier personnel Haldex farms out brake work The theme: Green and mean Dodge Ram gets interior upgrade BMW's 1-series coupe gets a soft-top counterpart Chrysler eye candy includes green jelly bean Chinese automakers increase their presence Concept offers a peek at Explorer's likely successor Ford goes global in styling its B-cars Forum concept is a clubhouse on wheels Dealers Simple safety: Green, amber, red Lexus SUV luxury will grow on you Personnel Gas prices boost Nissan car sales as trucks tank This year's U.S. sales forecast: Gloomy Ford: Tata is lead bidder for 2 brands Ex-Toyota manager goes to Audi Hyundai has new N.A. chief TRW buys Delphi brake assets Who's No. 1? Time for an official review Waning interest Solstice outguns Miata - again Once more into the legal fray? Lifan is the latest Chinese wannabe Things are looking up (and down) for MG Who has 1st Mustang - and what's it worth?

Automotive News - January 7, 2008

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