GM Sequel Concept

Press Release

Sequel's technology woven into intuitive design

Global design trends influenced the Sequel's design

Unfamiliar technology can be daunting, but carefully executed design elements in the Sequel combine a number of advanced technologies in a comfortable and inviting package.

"The Sequel's design is forward looking, but doesn't allow the underlying technology to overpower the driving experience," said Ed Welburn, GM vice president of design. "From the sleek, clean exterior to the intuitive interior, Sequel reinforces the viability of the technology and connects the user to the technologies in a very comfortable and familiar way."

The Sequel is comparable in size to the Cadillac SRX crossover vehicle, measuring 1,696 millimeters in length, 1,696 millimeters in height and riding on a 3,040-millimeters wheelbase. Those dimensions lend a recognizable, yet forward-looking shape to Sequel, while enabling the functionality of the vehicle's fuel-cell power system.

"The layout of the chassis and fuel cell system required a vehicle with a SUV-like stance," Welburn said. "Contemporary crossover-type vehicles also appeal to drivers because of their combination of car and SUV attributes - attributes definitely woven into the Sequel, such as a flat floor for easier cargo loading."

And while hinting of the future, Sequel's seductive design is rooted in conventional driving requirements. That's because the Sequel will undergo a series of real-world driving evaluations in traffic and at highway speeds, meaning designers and engineers had to incorporate production-vehicle criteria into the vehicle's design.

The design team made sure the Sequel looked at home on the road.

"We designed a realistic vehicle," said Robert Boniface, GM director of advanced design. "The importance of the Sequel is that it's a realistic, driveable and credible vehicle, so its design had to reflect that. It doesn't look like an outlandish, unreal dream machine."

A multitude of details tie elements of the exterior and interior together, as if they were parts of a precise, mechanical puzzle. Almost no corners or parting lines meet squarely; rather, they appear to "lock" together.

"All the intersecting elements may not be visible or readily apparent, but they work together to tighten the overall look of the vehicle," Boniface said. "As a result, the Sequel looks and feels extremely solid."

Global design trends also influenced the Sequel's design, both inside and out. Designers anticipated near-future trends in shapes, colors, lighting and materials by studying everything from Scandinavian furniture to the latest Asian-designed cell phones and sports shoes.

Distinct identity

The Sequel's bold look incorporates several attributes to satisfy its unique cooling needs.

Up front, the three large grille openings - a large, prominent grille in the center and two flanking inlets beneath the headlamps - feed air to a trio of large-capacity radiators. Besides providing cooling to the fuel cell stack, the radiators also cool the power electronics and front electric motor. On the hood is another air intake for cooling the HVAC (heating, ventilation and air conditioning) system.

More air inlets are surprisingly found at the rear of the vehicle, which feed outside air to cool the Sequel's rear wheel motors and battery pack. Typically, vents are placed on the side of the vehicle where the rear seat windows meet the back windows. The design team suggested developing rear cooling vents to enhance the exterior's styling.

"We asked the engineers if the vents could be moved," Boniface said, "and, after some careful studies of airflow, we learned the Sequel's thermodynamics actually improved with the vents under the taillights. So that's where we placed them."

The front-end styling also has unique headlamps and turn signals. The headlamps are made up of LEDs that magnify light through glass blades. This provides both superior light and a high-tech appearance. Also, the LED lights require less energy and create less heat than conventional headlamps. Their compactness and brightness allowed designers to develop lighting modules that are small enough to accommodate the radiator grilles beneath them. LED lighting carries over to the rear of the vehicle, too, making up the elements of the taillamps.

Sequel also has a full-length sunroof comprising separate sections that slide rearward. The windows and sunroof glass are tinted blue, which complements the light metallic green exterior color.

Interior integration

Sequel's interlocking design theme carries over to the interior. Elements are visibly integrated, from the floor panels to the seats. The vehicle's HVAC system is located under the hood instead of inside the instrument panel. Designers were able to rethink the role and placement of traditional controls. Instead of a center-dash control panel for the climate and audio system controls, individual controls for the driver and front passenger are located on the door armrests.

Even the air vents are unconventional. Air wafts out from behind the "floating" instrument panel via a high-volume/low-pressure HVAC system, similar to that of a cabin-pressurized airliner.

Other instrument panel features include:

• Transmission selector stalk featuring two positions: Drive and Reverse Keyless starting

And like the "floating" instrument panel, designers created a multipurpose, movable center console for the Sequel. It "floats" on a special track that moves the console closer to either the front or rear passengers, allowing access to the vehicle's audio/DVD/navigation systems, as well as Bluetooth USB ports and computer docking points. The console also contains a DVD/navigation screen and storage compartments for items such as DVDs or video game controllers.

"The center console can be configured to meet many lifestyle needs," said Anne Asensio, GM executive director, advanced design. "It can deliver driver-oriented information, or it can become the hub of a shared conversation space that connects passengers."

The five-seat concept vehicle features a front passenger seat that can rotate 180 degrees when the vehicle is parked, so that the front passenger can interact more easily with the rear-seat passengers.

Rear-seat flexibility allows multiple configurations including: forward/rearward adjustment, seat back reclining and a seat bottom that folds vertically to allow a flat load floor between the rear doors.

Contemporary colors including plum, rice and wasabi, as well as metal and wood accents, complement Sequel's airy cabin.

Designers also incorporated a new gel material for the armrests and load-floor strips. The silicone-rubber material is translucent, permitting backlighting through the material to give the interior a comforting, ambient glow. The lighting theme is continued in LED-lit trenches in the instrument panel.

Sequel is an easy-to-operate, intuitive vehicle. It has a traditional steering wheel, accelerator and brake pedal even though it uses by-wire technology. Controls and instruments also are recognizable and logically placed.

"Our aim is to deliver technologies that make sense and bring real benefits to our customers," said Welburn. "The Sequel concept delivers high value in an exciting design statement, with surprising functionality, and it is very good for the environment."

Next Generation Fuel Cell System propels GM's Sequel

Improved 480-km range is made possible by advances in high-pressure storage.

With a 25-percent more powerful fuel cell stack, GM's next-generation fuel cell power system helps Sequel achieve a 480-kilometer range and 0-100 kph acceleration in less than 10 seconds, while emitting only water vapor.

"Sequel is the first fuel cell vehicle in the industry that delivers the range and performance people expect from their current vehicles, bringing us that much closer to commercialization," said Byron McCormick, executive director of GM's Fuel Cell Activities.

Sequel's fuel cell stack and power module were designed and developed by GM engineers in Honeoye Falls, N.Y. The fuel cell power module is significantly simpler and more efficient than the module GM used to set a new world distance record for fuel cell technology in 2004 with a run of 9,640 kilometers through 14 European countries.

The fuel cell power module consists of the actual fuel cell stack, the hydrogen and air processing subsystems, the cooling system and the high-voltage distribution system. This power module delivers 73 kW of high-voltage power for the electric traction motors, as well as auxiliaries like HVAC (heating, ventilation and air conditioning), by-wire electronics and the battery.

"The system design has evolved and the components are becoming simpler, which is helping drive down the cost of technology and bringing us one step closer to reality," said Daniel O'Connell, head of GM Fuel Cell Product Engineering in Honeoye Falls.

Hydrogen introduced into the fuel cell is now directly converted to electric power to drive unprecedented torque control of all wheels. The two rear wheel hub motors including two inverters, as well as the power inverter module for the front electric motor, are developed by GM's Advanced Technology Center in Torrance, Calif. A high-voltage, lithium ion battery system provides extra power to the three electric motors during acceleration. It also stores power regenerated during braking to help extend the vehicle's overall mileage range.

Engineers at a GM fuel cell facility in Mainz-Kastel, Germany, integrated the fuel cell propulsion system into the vehicle package. The engineers linked the drive motor development with the rest of the system for a complete, vehicle-level, system solution. This led to an increase in the overall efficiency. It makes more power with less hydrogen, improving the performance and day-to-day operation.

GM's next-generation fuel cell also uses a new air intake system that is more efficient, quieter and lighter than its predecessor. The fuel cell stack, along with the cylindrical hydrogen storage tanks, is housed in a unique "skateboard" floor. Additional radiators are located under the Sequel's hood, directly behind the headlights, and in the rear of the vehicle, behind the taillights. These necessary design features help pull heat away from the fuel cell system, allowing Sequel to operate in hotter ambient temperatures.

"A fuel cell system is more efficient than an internal combustion engine, but its energy conversion is totally different and requires much more heat to be removed via the coolant," said Lothar Matejcek, project manager, GM Fuel Cell Activities, Mainz-Kastel. "With its three openings in the front, the extra opening for the HVAC and the two additional openings in the rear, you can easily recognize that Sequel was designed for heat rejection. We expect excellent performance at high ambient temperatures, typical of what you would experience in the desert."

Longer range

Sequel’s 480-kilometer range is made possible by advances in high-pressure storage that enable the vehicle to carry 8 kg of hydrogen, more than double that of GM’s Zafira HydroGen3 fuel cell vehicle. Developed in conjunction with Quantum Technologies (Nasdaq: QTWW), of Irvine, Calif., three lightweight, carbon composite tanks store hydrogen at 700 bars, compared to 350 bars in Hy-wire, Sequel’s predecessor. The larger tanks also enable a better ratio of stored hydrogen mass versus fuel storage system mass.

Within the novel skateboard floor are three cylindrical tanks. The carbon-fiber material, supplied by Toray Industries, of Tokyo, Japan, is strong and wraps the all-composite tanks. It provides a storage tank that is lighter than comparable metal tanks. The all-composite tanks have been validated to extremely stringent safety and performance standards representing harsh operating environments.

“Our skateboard chassis with the three-tank design is an excellent approach to providing a vehicle with a 480-kilometer vehicle range, without compromising overall interior and trunk space for the customer,� said Chris Borroni-Bird, director of GM’s Design and Technology Fusion Group and program director for Sequel. “Hydrogen storage technology will continue to evolve and, as improvements are made, we will translate this into greater range and smaller packaging designs.�

The electrical architecture of the Sequel consists of three systems. A high-voltage system provides power for the drive system, while a 42-volt system supplies the by-wire features. A 12-volt system powers conventional vehicle accessories such as the audio system and interior lighting. A high-voltage lithium ion battery system is an integral component in the Sequel’s propulsion system. It helps power the drive system at certain times, but also stores energy from regenerative braking, and thereby extends range. The lithium ion battery, supplied by Saft, of Bagnolet, France, offers 65 kW of peak power and weighs 65 kg.

Global effort

Hundreds of GM engineers and researchers and nearly 200 suppliers around the world have contributed to the technology infused in the Sequel’s fuel cell power module and propulsion system.

“The giant strides in efficiency and production viability, as seen in Sequel, simply would not have been possible without this large network of capabilities,� said McCormick. “Bringing these great minds together for such an important cause demonstrates GM’s commitment to fuel cells.�

Unprecedented Launch, Maneuverability And Stability make Sequel Safe and Fun to Drive

The electric motors reach a total power of 110 kW.

Sequel has taken today’s state-of-the-art, by-wire technologies and integrated them into a vehicle that is not only safe, but is a blast to drive by giving the driver greater control. The by-wire systems use electrical signals and actuators to operate the accelerator, brake and steering, and chassis-damping subsystems.

“This allows it to respond faster and have greater sensitivity, which provides for more precise vehicle control,� said Nick Zielinski, GM vehicle chief engineer, Advanced System Integration.

Sequel’s lower dominant structure has an inherently stable design with 50:50 front/rear weight distribution and a low center of gravity. Sequel also boasts, in addition to anti-lock brakes and StabiliTrak, a unique, all-wheel-drive traction system with front and rear torque control that further enhances vehicle stability and traction.

A transverse-mounted, three-phase, 60-kW electric motor drives the front wheels, and two, three-phase 25-kW electric wheel hub motors drive the rear wheels, resulting in a total power of 110 kW.

“By placing an electric hub motor in each rear wheel, there will be a 42-percent increase in torque when the vehicle begins to accelerate,� said Chris Borroni-Bird, director of GM’s Design and Technology Fusion Group and program director for Sequel. “All of that torque is available instantly and really makes Sequel fun to drive.�

The rear wheel hub motors and the power inverter module for the front electric motor were developed by GM’s Advanced Technology Center in Torrance, Calif.

“Wheel motors are a natural tie-in to all-wheel-drive, and they enable a higher level of traction and anti-skid control, improved steering and enhanced vehicle performance,� said Borroni-Bird.

Sequel’s by-wire technology may revolutionize driving

By-wire sub-systems are housed in skateboard chassis.

The GM Sequel will have enhanced braking, accelerating and handling characteristics by substituting by-wire technology for traditional mechanical systems.

By-wire technology essentially replaces mechanical and hydraulic linkages with electrical wires and actuators. By-wire systems convert driver commands, such as pressing the brake pedal or turning the steering wheel, into signals that actuate an electric motor to carry out the task.

“We have made tremendous progress in the design of by-wire technology, and we will continue to gain confidence in the durability and reliability of by-wire systems with extensive road testing of Sequel,� said Nick Zielinski, GM vehicle chief engineer, Advanced System Integration.

By-wire technology is likely to profoundly change the automotive industry by improving safety, making driving more enjoyable and allowing greater design freedom. It also could simplify maintenance because there are fewer moving parts that can wear out, and it can be more environmentally friendly than conventional vehicles. With steer-by-wire, for example, there is no reservoir of oil-based fluid. Similarly, the brake-by-wire system eliminates the need for brake fluid.

Nearly everything needed to power and control the car, including the hydrogen fuel cell and by-wire subsystems, is packaged into the Sequel’s 11-inch thick (28-cm) chassis structure. Working closely with suppliers such as Visteon, of Troy, Mich., for steer-by-wire; Pacifica Group Limited, of East Bentleigh, Australia for brake-by-wire; and Sachs, of Schweinfurt, Germany, for controlled integrated dampers, GM integrated these and other systems and ensured they work safely and seamlessly with other vehicle systems.

In addition to the chassis systems, by-wire technology also drives the precise, all-wheel-drive traction system. Unprecedented torque control of all wheels is possible because of the single front electric motor and two rear wheel hub motors, developed by GM’s Advanced Technology Center in Torrance, Calif. This system allows instant and almost infinite degrees of torque modulation to deliver the right amount of torque for changing driving conditions.

The ability to recapture braking energy using the front motor and rear wheel motors reduces the overall demand on the vehicle’s battery system. This improves fuel economy and contributes to the Sequel’s 300-mile range. Compared to conventional hybrid electric vehicles, Sequel has electric all-wheel-drive, which provides for more of the braking energy to be recaptured. Sequel’s brake-by-wire system also permits more seamless brake-blending between regenerative braking and conventional braking. This reduces the stopping distance.

In addition to chassis control, the Sequel’s fuel cell powers the climate control system. Sequel has a GM-patented hermetically sealed HVAC (heating, ventilating and air conditioning) system supplied by Mitsubishi Heavy Industries, Ltd., of Tokyo, Japan. In conventional passenger vehicles, the gasoline or diesel engine provides cabin heat and the power for driving the air conditioning system, which typically requires a bulky, in-dash HVAC system. In contrast, the Sequel moves the self-contained HVAC system out of the dash and into the space under the hood normally occupied by the engine. Moreover, by drawing in air through the hood, it allows the front radiators to focus on cooling the fuel cell more effectively so that the vehicle has full power, even on a hot day.

Learning tool

While Sequel represents a significant step closer toward a production hydrogen fuel cell vehicle, its advanced technology is already providing engineers with knowledge on how to extract even greater range and performance from the next generation of fuel cell vehicles. Expected progress in by-wire technology, for example, will enable the steering and brake systems to become considerably smaller and lighter, which will free up space for a larger fuel cell system and smaller battery pack. In addition, continued advances in hydrogen storage will provide the opportunity to lower the floor height and add more power to the fuel cell stack.

“Anything that allows us to reduce the size of the battery pack and storage tanks means more room for a larger fuel cell, which increases vehicle performance,� Zielinski said.

Specifications: GM Sequel