A new ParadiGM in hybrid powertrains

At the North American International Auto Show in January, General Motors Corp. announced that it has developed a hybrid powertrain that can be applied to a range of passenger vehicles. It will debut in 2004, according to GM Vice Chairman Harry J. Pearce, with the first application being an SUV. It will join another hybrid full-size truck system for 2004.

GM's ParadiGM hybrid system. Click to enlarge

The ParadiGM SUV hybrid system combines a V6 or I4 engine with a pair of ac electric motors and a battery pack. The powertrain gets 166 kW (220 hp) from a 3.6-L V6 in addition to 24 kW from the two electric motors. The system is being designed for use on GM's Epsilon global midsize platform, which Saab and Opel helped develop, and may be deployed on a variety of vehicle types in North America, Europe, Australia, and Asia, including SUVs, crossover vehicles, and sedans. At least 7000 SUV hybrids should be produced in the first year, according to Pearce, with other vehicle types appearing later depending on market conditions. The new powertrain will complete a range of hybrid options being developed by the company ranging from two-seat cars to urban transit buses. The combined volume of sales from all GM hybrids could exceed 100,000 units by the end of this decade, Pearce predicted.

Instead of using the powertrain on a vehicle engineered from the ground up for maximum efficiency, GM chose to develop "a practical drivetrain that can power a variety of our vehicles," according to Pearce, and one that most consumers are actually willing to buy. This approach in applying technology in high-volume solutions - converting popular vehicle styles into more-efficient hybrids - is intended by GM to save far more gasoline than creating a small niche vehicle that will sell in small numbers.

The planned SUV will get about 20% better fuel economy than a nonhybrid version - or about 35 mpg (city/highway composite) - and is targeted to achieve lower tailpipe emissions. GM intends to market the ParadiGM SUV at a price similar to a "comparably-equipped vehicle." The battery pack is smaller than that in a purely electric vehicle - and just 1/5th the weight - and it acts mostly as a supercharger on the IC engine for passing and quick acceleration. GM expects the SUV, equipped with an automatically shifted six-speed manual transmission, to accelerate from 0 to 97 km/h (0 to 60 mph) in less than 7 s.

The heart of the ParadiGM system is its innovative transaxle. It links the full-sized engine with the electric motors, differential, and air-conditioning compressor. The entire package, including the IC engine, fits transversely over the front axle. The system was engineered to overcome some of the shortcomings of the small, mild hybrids currently available. Notably, it efficiently powers the air-conditioning system, even when the engine is off. Air-conditioning is the second-largest consumer of a car's energy after propulsion and in the early production hybrids, created serious problems for efficiency and performance, according to GM. Because the air-conditioning compressor will be driven by the transaxle, it can be turned by the IC engine, one of the electric motors, or by regenerative braking.

Each electric motor has three operating modes: as a motor to drive the car's differential and propel the car; as a starter motor for the IC engine; or as a generator to convert energy created by the engine or by the vehicle's regenerative braking into electricity that is stored in the batteries. The vehicle's range on battery power alone is quite limited to save the weight and expense of a large battery array. Initially, the vehicle will rely on a 42-V lead/acid battery pack with 25 kW of peak power, but GM is investigating other battery technologies.

Essentially, the IC engine is the primary source of power, but it will be turned off when power demand is low to save fuel. The vehicle will "idle" and accelerate away from the traffic signal on electrical power alone.

The ParadiGM system builds on the experience of last year's Precept concept car and is a further refinement of the hybrid drivetrain developed for that project by GM's Advanced Technology Vehicles team. Precept relied nearly equally on a 40-kW (54-hp) IC engine and two electric motors to achieve an 80 mpg composite rating. The engine delivered most of the propulsion, with the motors providing low-speed propulsion and doubling as electrical generators.

- Kevin Jost

Torvec's icy idea for treads and tires

Torvec's FTV (Fast Tracked Vehicle) will be one application for the new ice-traction system for rubber treads and tires.

A technology licensed late last year by Torvec, Inc., is claimed to increase the traction of rubber on ice by a factor of twenty. An ice physicist from Dartmouth College, Dr. Victor Petrenko, has turned this technology into an ice-traction system for rubber treads and tires. The system involves equipping vehicles with smart treads that "grab ice," providing vehicles with as much traction on ice as when driving over dry pavement, ultimately preventing many winter driving accidents. "Petrenko's system could give our Fast Tracked Vehicle (FTV) maneuverability and control in icy conditions," said Keith Gleasman, Torvec President. "Our FTV already navigates the roughest terrain and goes places a 4x4 can't, so an ice traction system opens exciting new markets."

BFGoodrich has also licensed the technology, mainly for airplane and marine applications, especially for deicing airplane wings. Torvec acquired the license for land-based applications such as windshields, rubber tracks, and tires for cars, trucks, and railway boxcars. Dartmouth has a policy of licensing its technology to one large company and one small entrepreneurial company.

Petrenko's research was conducted at Dartmouth's Thayer School of Engineering and supported by grants from the Army and the National Science Foundation. He discovered that opposing electrical charges are the secret glue that adheres ice to surfaces. On a molecular level, ice molecules tend to line up in the same direction, so the ice is positively charged or negatively charged. When, for example, positively charged ice touches another surface it gives that surface a negative charge and creates a strong bond. This phenomenon is what makes ice cubes stick to fingers; children's tongues stick to frozen swing sets; and ice stick to windshields, windowpanes, gutters, trees, and most anything else it touches.

In the inside-out world of ice crystal physics, adding ice to tire treads actually increases traction. The mechanics of the ice-traction system are relatively straightforward. A mild electrical current through the tread creates an electrical charge on its surface. This charge has the opposite polarity from the ice on the road and creates a thin coating of ice on the tire. The two oppositely charged ice surfaces can then grip each other, providing the traction necessary to steer and slow a vehicle over ice.

"We envision an ice-traction system that engages and disengages to adjust for different road surfaces," said Gleasman. "On pavement the system is off, but as soon as the tread hits ice, the traction system is activated. Micro-thin electronic sensors and conductors could be embedded in the tread of our FTV's rubber track or in a tire. Tire manufacturers are already looking at incorporating traction sensors and other micro-electronics into tire and wheels, so this would not be an enormous change in the manufacturing process."

Torvec is also "rushing to market" with an invisible windshield polymer that will repel ice from the glass surface. The polymer conducts a low voltage current, comparable to that used to run car clocks. The company claims the windshield will repel ice without heat and defrosting or chipping and scraping. Windshields are manufactured by sandwiching a "tinting glaze" between two layers of tempered glass. Torvec's anti-icing polymer will be part of the micro-thin filling invisible to the human eye.

The same Dartmouth deicing technology used in rubber treads and tires will be used in Torvec's ice-repelling system, which will be made for both replacement windshields and new automobiles.

- Jean L. Broge