Technology Keeps ICE Plugged In

As the industry begins a new season of auto shows and fresh model introductions, a flurry of technological advancements is pushing the internal combustion engine in new directions both exhilarating and maddeningly complex for powertrain engineers from Detroit to Stuttgart to Tokyo.

Rather than accepting the notion the ICE soon will be outmoded, engine developers hold it up as the magnificent engineering feat it is, carrying on a tradition that began more than 100 years ago — with no end in sight.

Auto makers are not the only ones leading the charge.

Independent researchers from all corners are engaged in efforts to combine the best attributes of diesel and spark ignition into one engine. They are exploring new biofuel formulations that lessen dependence on petroleum. And they continue to find new ways to reduce tailpipe emissions.

Auto makers are planning aggressive rollouts of new vehicles equipped with gasoline engines benefiting from cleaner burning direct-injection technology. They are developing diesel engines that can operate as cleanly as gasoline engines.

Honda Motor Co. Ltd., for instance, is expected to make a splash soon with the introduction of an all-new turbodiesel equipped with an innovative catalytic converter that allows the diesel engine to meet Environmental Protection Agency Tier II, bin 5 emission standards.

The new converter is simpler in design than current diesel exhaust systems with urea injection — and thus potentially less expensive, says Motoatsu Shiraishi, president of Honda R&D Co., the auto maker's wholly owned research subsidiary. No urea tank, no urea heaters, no accompanying sensor and injector.

Honda's system stores NOx in the catalyst and converts it into harmless nitrogen during normal engine operation.

NOx stored below the surface of the catalyst substrate is converted to ammonia (NH3) during a brief and controlled rich-combustion phase and moves to the platinum-coated catalyst surface. There it reacts to form harmless nitrogen and water.

HCCI Research Advancing

Joining auto makers' search for better ICEs is the Massachusetts Institute of Technology, where researchers have unveiled a spark-ignition engine that can switch to spark-free combustion under certain driving conditions.

The MIT team, which presented its research at the 2007 International Fuel and Lubricants Meeting in Kyoto, Japan, has devised a unique way to switch from a conventional gasoline engine's sparkplug-initiated ignition to “homogeneous charge compression ignition,” or HCCI, to boost fuel economy.

A fuel and air mixture is injected into the cylinder of an HCCI engine and creates spontaneous combustion as the piston compresses it. The spontaneous ignition, without help from a sparkplug, resembles what happens in a diesel engine.

Because HCCI combustion takes place throughout the cylinder at lower temperatures than typical of a compression-ignition diesel, it minimizes NOx emissions that are inherently higher for diesels. Also, by spreading fuel in low concentrations throughout the combustion chamber, particulate emissions are reduced.

The MIT scientists had to create a way to ensure ignition occurs in an HCCI engine precisely when the piston is positioned for its power stroke.

“It's like when you push a kid on a swing,” says William Green Jr., a professor with MIT's department of chemical engineering. “You have to push when the swing is all the way back and about to (move forward),” he says. “If you push at the wrong time, the kid will twist around and not go anywhere. The same thing happens to your engine.”

The MIT scientists claim the mode-switching capability could appear in production models in a few years, although top powertrain engineers are not nearly as optimistic.

“Production HCCI engines are unlikely before 2013,” says Tom Stephens, group vice president-GM Powertrain and Quality.

In August, GM unveiled a pair of HCCI prototype vehicles (an '07 Saturn Aura and '07 Opel Vectra) with test engines based on 2.2L DOHC Ecotec 4-cyls. making 180 hp and 170 lb.-ft. (230 Nm) of torque.

Both powerplants offer a 15% fuel savings compared with similar port-fuel injected gasoline engines, while also meeting current emissions standards, GM says.

The auto industry has been working toward the development of functional HCCI engines for the past 30 years, says Uwe Grebe, executive director-GM Powertrain Advanced Engineering.

Enabling technologies for the GM concept include direct-injection gasoline (DIG), dual electric camshaft phasing, variable valve lift and timing (VVT) and closed-loop cylinder-pressure sensing.

A key benefit of HCCI is the ability to achieve diesel-fuel economy without the need for expensive exhaust-aftertreatment systems to reduce excessive NOx emissions.

Upon startup and during higher engine loads, the HCCI engine operates as a conventional gasoline 4-cyl. Under moderate loads, such as steady cruising, the compression-ignition combustion mode takes over for improved efficiency.

GM's HCCI system is adaptable to conventional gasoline engine architectures and can operate on any gasoline/biofuel blend. The main hurdle for commercialization remains the refinement of the complex electronic controls governing the switch to HCCI mode.

VW Blends Diesel, Gas Attributes

At an event earlier this year at a test track near Wolfsburg, Germany, VW offered test drives of a Golf prototype equipped with gasoline compression ignition (GCI) and a Touran multipurpose vehicle powered with VW's new combined combustion system (CCS).

Although the two approaches yield improvements in fuel economy and emissions and maximize the benefits of gasoline and diesel engines, the technologies are vastly different.

The GCI concept — which is closer to production than CCS — employs HCCI on a production-like normally aspirated 1.6L FSI DIG and achieves fuel economy nearly on par with that of a diesel.

The GCI engine runs on regular unleaded gasoline, slashes emissions of carbon monoxide 70%, NOx 99% and hydrocarbons 17%, compared with the production gasoline engine on which it is based. Plus, the engine emits no particulates or soot.

Driving VW's GCI concept engine is enjoyable and seamless. Startup occurs in conventional gasoline operation and remains there during higher loads and engine speeds.

But during moderate speeds and lighter engine loads between 25 and 62 mph (40 and 100 km/h), sparkplugs shut off and the engine enters a state of “controlled self-ignition,” VW says.

Fuel-economy improves between 5%-10%, based on the new European driving cycle, says VW, which considers GCI to be a stepping-stone to achieving an even greater technological breakthrough with its CCS.

The powertrain concept, which could become a reality within the next decade, merges the principles of DIG with diesel direct injection, branded as TDI by the auto maker.

The gasoline engine contributes a homogeneous fuel-air mixture and low emissions to the CCS concept, while TDI offers low fuel consumption and compression ignition.

On the CCS engine — a heavily modified 2.0L 4-cyl. TDI powering the Touran driven in Wolfsburg — fuel injection occurs in homogeneous operation while the piston travels upward and compresses the charge.

Using common-rail injectors taken from the production diesel engine, the injection volume can be distributed among different cycles and precisely metered.

While the piston travels upward, the fuel and air are compressed and heated and the fuel vaporizes, producing a largely homogeneous mixture comparable to that of a DIG engine.

Combustion begins in homogeneous mode, without requiring an external spark, as with a diesel.

Like the GCI concept, the CCS engine operates at a high EGR rate, and the oxygen-poor re-circulated exhaust gas ensures combustion occurs at a temperature low enough to prevent the formation of NOx, VW says.

The uniform combustion process allows for only a small amount of soot to collect, in contrast to the diesel.

Alternative Fuels

U.S and European auto makers also are doing much in the area of biofuels.

GM, for instance, currently offers 14 cars and light trucks and vans in the U.S. that can run on corn-based E85 (an ethanol/gasoline blend) and is pledging to build 400,000 additional units annually if the necessary infrastructure is in place.

The auto maker already has 2 million flex-fuel vehicles (FFVs) on the road in the U.S., Stephens says. In Brazil, FFVs make up more than 95% of GM's fleet, and in Europe the Saab 9-5 BioPower model is the best-selling FFV.

Cylinder Deactivation Taking Off

Another technology designed to improve fuel economy in large-displacement engines is cylinder deactivation.

Chrysler LLC says it has tweaked its fuel-saving Multiple Displacement System to activate more readily.

Featured on Chrysler's vaunted 5.7L Hemi V-8, MDS deactivates four cylinders when the engine is operating under optimal conditions, as occurs when cruising at highway speeds without headwinds. But for '08, MDS is available at slightly lower rpm rates, says Craig Love, vice president-rear-wheel-drive product teams.

The move narrows what Chrysler insiders call the “no-fly zone,” Love says. The “no-fly zone,” which includes idle, is the rpm range where MDS causes the Hemi to exhibit noise, vibration and harshness inconsistent with smooth performance.

Overall, Chrysler claims MDS can boost fuel economy up to 20%.

Honda has set a new benchmark for cylinder deactivation: Its all-new Accord sedan sports a powerful 3.5L V-6 that can shut down certain cylinders in two separate stages.

Honda first debuted its variable cylinder management (VCM) system — which converted a V-6 to an inline 3-cyl. during light cruising — in the '05 Accord Hybrid. It since has been fitted to the Odyssey minivan and Pilot cross/utility vehicle.

The new VCM system differs in that at highway speeds, moderate cruising and ascending mild hills the '08 Accord's 3.5L SOHC V-6 switches to a staggered V-4 layout, whereby the left rear and right front cylinders are idled for better efficiency in a greater number of driving situations, the auto maker says.
Tom Murphy with Herb Shuldiner,
Roger Schreffler, Mike Sutton,
Eric Mayne and Barbara McClellan

‘Electrification’ of Vehicles Inevitable, but Gradual

Comedian and political pundit Bill Maher frequently jokes, “We'll all be dead” before hydrogen-powered vehicles hit the road.

If that's the case, the push to develop emission-free, fuel-cell powered vehicles may be the most elaborate public relations ploy ever.

Even South Korea-based Hyundai Motor Co. Ltd. now has a serious fuel-cell program, joining the rest of the world's largest auto makers, of which all have major ongoing development efforts.

Hyundai hopes to begin producing fuel-cell vehicles in small volumes, approximately 10,000 units annually, by 2010. Mass production should begin by 2015, the auto maker promises.

That goal is similar to most other auto makers, with Honda Motor Co. Ltd., DaimlerChrysler AG and Ford Motor Co. each shooting for the 2010-2015 timeframe.

No Japanese auto maker plans to mass-produce a fuel-cell vehicle until about 2015, but General Motors Corp. says it wants to be building millions of FCVs by 2020.

Larry Burns, vice president-research & development and strategic planning at GM, says despite the fact the auto industry has doubled fuel economy in the past 30 years and reduced tailpipe emissions in the U.S. 98% from the 1960s, the exponential growth of vehicle ownership worldwide has the potential to have a huge and possibly negative impact on society and the environment.

That's because growing numbers of cars and trucks will guzzle billions more gallons of fossil fuels, spew more emissions and clog roads.

By 2020, there could be as many as 1.1 billion vehicles on the road, and yet that would represent an ownership rate of 15%, just three percentage points higher than today's global 12% ownership rate, Burns says.

If every person in China were to enjoy the same standard of living as in America, he warns, global oil production would have to double from today's levels to meet demand.

In Burns' view, the industry has no choice but to create new, completely electrified vehicles such as GM's fuel cell-powered Sequel prototype that emits only water vapor and whose functions all are controlled by electronics and electric motors, instead of mechanical devices.

Promising to have fuel-cell vehicles in showrooms by 2012, GM completed a historic 304-mile (489-km) test drive of its Chevrolet Sequel FCV on one tank of hydrogen earlier this year.

Driving from GM's Fuel Cell Activity Center in Honeoye Falls, NY, to Tarrytown, NY, the Sequel made the trip carrying 18 lbs. (8 kg) of hydrogen, the equivalent of 16 gallons (61 L) of gasoline.

The Sequel's fuel stack generates 98 hp, which provides the vehicle a top speed of 100 mph (160 km/h).

GM announced a year ago plans to lease more than 100 FCVs this fall to the general public in the form of Chevrolet Equinox cross/utility vehicles.

A company spokesman says leasing will be focused on areas where there is a hydrogen infrastructure to permit convenient refueling, such as Westchester County, NY; Burbank, CA; and Washington.

Honda Motor Co. Ltd. has announced an expanded U.S. leasing program to general retail customers for its next-generation FCX experimental fuel-cell vehicle, as well.

The next-generation FCX, with a roomier interior comparable with that of a midsize car, “will cost us less to produce due to various advancements that get us closer to mass production,” a Honda spokesman tells Ward's at an FCX test drive in Washington earlier this year.

Honda declines to reveal exactly how many FCX units it plans to lease in 2008.

A more powerful, yet smaller fuel-cell stack than in the previous-generation FCX generates 134 hp that gives the electric motor a maximum output of 127 hp, says Ben Knight, vice president, Honda R&D Americas Inc. Maximum torque is 186 lb.-ft. (256 Nm).

The new powerplant is 396 lbs. (180 kg) lighter and about 40% smaller than in the previous generation. That is about equal to a V-6 hybrid-electric powertrain, Knight says.

Honda's 5-year targets for the car include a further 10% to 15% reduction in stack size, a 15% to 20% reduction in the power control unit's size, and the 300-mile driving range.

Meanwhile, Honda's 2020 price target for its FCV is @4 million ($35,000), roughly the same as an upper-grade Accord. If it achieves that target, the auto maker estimates FCVs will account for 5% of Honda sales in North America.

Toyota Motor Corp. recently began real-world tests of a fuel-cell hybrid-electric vehicle (FCHV) in Japan, loaning a prototype to a transport company in Nagoya.

Based on the midsize Kluger (Highlander in the U.S.) cross/utility vehicle and registered as a commercial vehicle, it will be fueled at a hydrogen station at the Central Japan International Airport.

Toyota plans to use the project to obtain a wide range of data needed for series production of FCHVs.

Toyota says its Kluger FCHV is the closest vehicle yet to the ultimate eco-car.

It features a hybrid-electric system powered either by onboard batteries or fuel cells using pressurized hydrogen gas.

The auto maker says the FCHV's current cruising range is about 200 miles (322 km) and engineers are aiming for further improvements in fuel-cell and system efficiency to match the cruising distance of a vehicle powered by a conventional internal-combustion engine.

Hybrid-Electric Vehicles

While even proponents still are not certain exactly where and when fuel cells will take off, the electrification trend already is clearly established in the form of hybrid-electric vehicles, which use electric motors, wiring and electronics architectures similar to those used for FCVs.

HEV-leader Toyota hopes to sell 1 million HEVs globally by 2012, roughly 10% of the auto maker's total sales.

Honda also has set an aggressive sales target of 200,000 units for a new compact HEV (smaller and cheaper than the Civic Hybrid) it plans to introduce in 2009. Combined with Civic and Accord hybrids, Honda's annual HEV sales total could top 250,000.

Now that Detroit's Big Three, Nissan Motor Co. Ltd. and Mazda Motor Corp. are offering a variety of new HEV models in the U.S. as well, buyers could have 25 or more HEVs to choose from by the '09 model year. Choices will include both mild and full hybrids on fullsize SUVs as well as cars.

And even though European auto makers initially scoffed at HEVs, they too are jumping on the bandwagon.

France's Institut Francais de Petrole is even working with PSA Peugeot Citroen in a program to develop a diesel-hybrid powertrain by 2010.

Porsche AG promises a dramatic reduction in fuel consumption for its Cayenne HEV, due by the end of the decade.

The Cayenne hybrid CUV is expected to achieve combined city/highway fuel economy of approximately 24 mpg (9.8 L/100 km), the auto maker says, noting additional advancements may boost that figure to 26 mpg (8.9 L/100 km).

This is a significant gain over the conventional Cayenne lineup, which manages as little as 13 mpg (18.1 L/100 km) for the 500-hp Cayenne Turbo.

The figures also are similar to those put forth by GM for its new fullsize Chevrolet Tahoe and GMC Yukon hybrid SUVs, set to roll into dealerships by the end of the year.

Like the GM HEV two-mode drivetrain, the Cayenne will be a full-hybrid design, with power coming from an internal combustion gasoline engine, electric motors and batteries, or any combination of the two.

Porsche declines to specify what batteries (nickel-metal hydride or lithium-ion) or what engine will be used for the Cayenne hybrid when it reaches production.

Whatever the layout, it will have to be flexible, as the core drivetrain components will make their way into a hybrid variant of the upcoming '09 Panamera 4-door coupe, as well as the Audi Q7 and Volkswagen Touareg hybrid CUVs, both of which share the Cayenne's basic structure.

Mercedes-Benz is planning a light hybrid approach for its future S-Class, says a source close to the project at the Hybrid Development Center in Troy, MI.

When it was DaimlerChrysler AG, the emphasis was on bringing hybrids to Chrysler Group projects first. The new Chrysler LLC will have full hybrid powertrains on its Dodge Durango and Chrysler Aspen SUVs beginning some time next year.

The vehicles will feature Chrysler's 5.7L Hemi V-8 mated to the two-mode hybrid transmission and electric motors developed in a joint venture with GM and BMW AG. The hybrid powertrain is expected to boost fuel economy up to 25%.

Now that those projects are nearing production, the emphasis has switched to Mercedes-Benz.

The heavy, expensive and profitable S-Class flagship sedan needs a hybrid powertrain to lower its fuel consumption to meet future European goals, and relatively inexpensive electric motor-generators will allow the engine to shut off at stop lights and in traffic jams.

The Hybrid Development Center has been funded by BMW, GM and DC. It is unclear how the DaimlerChrysler breakup will affect Chrysler's continued participation in the JV.

Plug-In Hybrid-Electric Vehicles

Sandwiched between totally electrified FCVs and HEVs are plug-in hybrid vehicles. Barely on the radar screen until GM introduced its stunning Volt concept at the North American International Auto Show last January, PHEVs now are the subject of tremendous interest and debate throughout the industry, with Toyota, Ford and others also showing off concepts.

The Volt combines electric power with a 1.0L, 3-cyl. turbocharged engine. When electric power wanes, the engine, which can burn gasoline or alternative fuels, kicks in to generate power for the electric motor.

Engineers stress that advanced Li-ion batteries will be key to bringing PHEVs to market.

While Li-ion batteries have been employed in consumer electronics, power tools and various other applications for some time, they are not ready to safely power vehicles for 10 years or 150,000 miles (241,402 km), the lifespan GM says is needed to effectively market Li-ion battery systems in its next-generation hybrid-electric vehicles.

Advanced PHEVs, such as GM's upcoming Saturn Vue variant and production versions of the Chevrolet Volt electric concept car, will require stronger electric power sources that operate over a wider state of charge, says Joe Lograsso, engineering group manager-Hybrid Energy Storage Systems.

Current HEVs use NiMH batteries and usually operate in their middle range of charge. By keeping the batteries from fully charging or discharging, damage is reduced and longevity is increased.

But PHEVs and other electric vehicles such as the Volt can drain their batteries almost completely in electric-only mode, thus requiring the superior performance of Li-ion systems.

Li-ion batteries generally have a greater specific discharge power and higher energy density than NiMH batteries, Lograsso says. They also are 40% lighter and 20% smaller.

Where Li-ion technology falls short is in its robustness, abuse tolerance and shorter life expectancy compared with NiMH. Li-ion batteries also require more sophisticated electronic controls, have poor cold-weather performance and initially will be costly to produce until volumes ramp up.

GM and Li-ion battery partners Johnson Controls-Saft Advanced Power Solutions LLC, Cobasys LLC and A123Systems are aware of these concerns and are moving forward with different separator materials, better cell designs and more effective test protocols, Lograsso says.
Drew Winter with Michael Sutton,
Christie Schweinsberg, William Diem,
Eric Mayne and Roger Schreffler

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