For years the hydrogen fuel-cell vehicle has been a major research project. There have been several one-off vehicles developed to test stack reliability, tank construction and the like, but General Motors has taken it further, a purpose-built hydrogen fuel-cell vehicle that meets U.S. federal safety requirements. Its Chevrolet Sequel fuel-cell concept, a purpose-built crossover, also launches new technologies, including e-corner and the most advanced drive- and brake-by-wire systems. Making the vehicle operational and credible was a key goal for the Sequel team as GM continues on its path to developing a marketable fuel-cell system by 2010.
“What we have done is nothing less than re-invent the automobile,” says Larry Burns, GM vice president of research and development and strategic planning. That might be a stretch, seeing how GM has not publicly said it will PRODUCE the Chevrolet Sequel by 2010, rather it will have the technologies under the skin validated and priced for production intent by that time. Before moving along in the technology debate, there’s another item here that’s equally important from a messaging standpoint and that is branding. As you may recall, when the Sequel made its public debut in 2005, it was branded as a GM product, not limited to any specific brand. Now the automaker has decided it will task Chevrolet with taking the lead for fuel-cell vehicle development as, both the Sequel and a test fleet of 100 hydrogen fuel-cell Chevrolet Equinoxes to be launched in 2007, attest. The reasoning behind using Chevrolet as opposed to Cadillac or any other GM brand is because of its global reach and affordability, says Burns. After all, the first hydrogen fuel-cell vehicles may not be sold in the U.S., but other developing countries—think China, India—where Chevrolet also has roots, particularly as the number of automobiles in service around the globe is expected to grow to 1.1 billion by 2010.
The vehicle was designed by GM’s advanced vehicle design team, with Bob Boniface, director of GM’s advanced vehicle design, taking the lead on exterior and interior design. While Roush Industries built the two finished vehicles, Boniface and his team worked on a nine-month schedule to take the concept and turn it into a drivable model. “We did the concept car in our studio in ’05 and the drivable version concurrently, almost from the same math release. We always knew there was going to be a drivable vehicle, but we didn’t know what it was going to be branded,” Boniface says. Carrying Chevrolet cues into the finished product was the least of Boniface’s worries, as he had to design a road-worthy vehicle around technologies that had yet to be validated. The necessity to place the fuel cell stack and tanks under the floor prohibited his team from designing anything other than a crossover, due to packaging constraints. Aerodynamics also posed another set of issues, since the stacks require a vast amount of air cooling to prevent overheating. “We had to have good space for the occupants, the floor needed to be flat and we had to have a lot of cooling openings on the exterior,” he says. “But we also knew we didn’t just want to make a jellybean with a bunch of holes cut into it.” Boniface took influences from high-end electronics manufacturers when designing the Sequel’s headlamps and details around the grille openings. But he’s most pleased with how the vocabulary created in the bodyside of the concept—particularly the line work and the rear flare—was carried over to the drivable models. He’s equally pleased with how the front and rear cooling vents are integral to the overall design. “We took a piece of functional criteria and turned them into very integrated design elements,” he says. The original plans for the rear vents had them placed on the rear bodyside of the Sequel, but that was not visually appealing, Boniface says, dubbing the original vents “ears.” “I was unhappy with the location of the rear vents, to say the least,” he adds. After conducting a series of pressure mapping tests it was determined that the batteries would get enough cool air flow if the they were located on the liftgate of the Sequel, which is where they ended up. Once the functional design requirements were met, it was time to get real, as the design team was tasked with taking a number of off the shelf pieces and incorporating them into the Sequels interior. The steering wheel, for example, is from the GMT-900 truck platform, as is most of the switch gear, while seats and air vents were taken from the Chevrolet HHR parts bin. The move toward a drivable product also forced designers to nix the rear hinged rear doors and replace them with conventional hinged doors. Finally, the team had to turn the non-descript GM-branded design into a Chevrolet theme, with the most extensive changes made to the Sequel’s front grille, which got a wide center crossbar and gold Chevy bowtie emblem. The Sequel is said to be a hint at the future grilles design vocabulary for successive Chevrolet products. Boniface says he wanted the Sequel to be “credible.”
Credibility means taking risks and Sequel is a huge technological leap in terms of systems integration. The technology story starts with the expansive use of steer- and brake-by-wire technologies. Visteon provided the steer-by-wire technology, which features a variable gear ratio set-up. The steering system can be adjusted via the click of a mouse and the basic architecture of the system can be shared across various vehicle platforms from compact sports cars to full-size trucks. An added benefit of using by-wire steering is the ability to easily reconfigure vehicles for right- or left-hand drive, while at the same time using the steering system to support vehicle stability control programs. The brake-by-wire systems, supplied by PBR International, provide smoother and more exact braking, along with the ability to meet the needs of various vehicle configurations, albeit with minor changes to the caliper sizes and software programs. In order to assure the reliability of the by-wire technology, the suppliers built in triple redundancy in case bugs developed in the electronics. Sequel uses a 42-volt electrical architecture with the latest FlexRay communications network managing 10 controllers for the various by-wire and suspension control systems. The fuel cell power module was designed by GM engineers in Honeoye Falls, NY, and is made up of a fuel cell stack, hydrogen and air processing subsystems, cooling systems and a high-voltage distribution system delivering 73 kW of power for the electric traction motors, along with power for auxiliary systems including heating and ventilation, by-wire electronics and battery systems. The hydrogen is directly converted from the fuel cell to electric power and is used to provide power to the two rear wheel hub motors developed in conjunction with Lucchi R. The motors control each wheel independently and produce 60 kW of electricity with a torque rating of 800 NM. Power from the cell is also used to control the power inverter for the front electric motor, which was developed by engineers at GM’s Advanced Technology Center in Torrance, CA. David Ouwerkerk, one of the engineers that worked on the wheel hub power system, which GM has dubbed “eCorner,” says the system provides a number of key benefits, including the elimination of traditional half shafts and the gearing associated with traditional axles.
While development proved to be a formidable task, Sequel represents an equally challenging outlook when it comes to the future of vehicle manufacturing. GM’s Burns envisions a day when traditional transmissions and internal combustion engines will be a thing of the past, meaning the industry will no longer need the tooling that make gears, pistons, valves, manifolds, engine blocks and the like. He sees the day when fuel cell stacks are produced line-side, in conjunction with the vehicle itself. The process will go somewhat like this: coils of stainless steel and rolls of polymer film will be delivered directly to the plant where the stack will be manufactured. Once the stack has reached its desired size, it will then be sent to the assembly hall where it will be married with the eCorner units and fuel tanks. Line operators will then add a bit of hydrogen and the vehicle will propel itself down the trim line, where workers will add the interior components and body. Since the basic architecture of the stack is consistent across all vehicle lines—the only difference will be the number of cells, which will indicate power output—the need to have massive powertrain facilities will be removed from the system. Likewise, the ability to use numerous by-wire systems will reduce the number of unique steering, brake and control modules used for each vehicle. Burns, who predicts some of the changes will take root as soon as 2010 and as late as 2020—he sees by-wire systems gaining acceptance earlier than full fledged fuel cells—has some advice for tooling manufacturers looking to maintain their competitive edge: “They need to look at this as an opportunity to innovate. I remember a saying that seems pretty appropriate on this topic: ‘do onto yourself before others do onto you.’ I think that’s the attitude machine manufacturers need to think about.”
While Burns and his team may have this grandiose vision of populating the world with hydrogen fuel cell powertrains, there’s a critically important piece of the puzzle that needs to be solved before declaring a revolution: fuel availability. As the price of oil remains relatively high and oil companies continue to rake in record-setting profits, it’s hardly conceivable this industry will embrace having to invest billions of dollars to develop a new fueling infrastructure. That’s not entirely true, according to Phil Baxley, president of Shell Hydrogen, a division of the Shell Oil empire, who says his company is making the investments to bring hydrogen to the market. He points to a single Shell hydrogen pump located outside of Washington, D.C. —that’s one out of 13,000 stations Shell has in the U.S.—as proof of Shell’s commitment to building the hydrogen highway. He says Shell has a project dubbed “Lighthouse” that will call for the expansion of hydrogen fueling stations throughout the U.S. in the coming decades, although the exact number remains uncertain. Shell will plan its initial focus on building stations in Southern California, including Los Angeles, Long Beach, Torrance, Irvine and Ontario by the 2015-2025 timeframe. The plan is to have between 10-20 stations in each major population center of the U.S. shortly thereafter, depending on vehicle availability. Baxley acknowledges that some oil companies are likely to adopt hydrogen fuels through a process that will involve “a lot of kicking and screaming,” but he says automakers must move first in order to prove there is demand. The old chicken and the egg scenario rears its ugly head again.