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Sequel
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Fuel Cell
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DETROIT - 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.
Contact:
Scott Fosgard
GM Advanced Technology Communications
Office: 586-947-3295
Cell: 586-899-2582
Fax: 586-947-9259
E-mail: scott.fosgard@gm.com
Renee McClelland
GM Advanced Technology Communications
Office: 586-492-7461
Cell: 313-418-3974
Fax: 586-947-9259
E-mail: renee.mcclelland@gm.com