Friday, June 12, 2009

Gas-Electric Hybrids

NEW TECHNOLOGIES



Gas-Electric Hybrids
The Toyota Prius, top, a four-seat hybrid electric vehicle (HEV), was the first HEV to be marketed when Toyota introduced it in Japan in 1997. The Honda Insight, bottom, a two-seat HEV, followed in 1999 when it was sold in both Japan and the United States. The Prius had its U.S. debut in 2000.
Pollution-control laws adopted at the beginning of the 1990s in some of the United States and in Europe called for automobiles that produced better gas mileage with lower emissions. The California Air Resources Board required companies with the largest market shares to begin selling vehicles that were pollution free—in other words, electric. In 1996 General Motors became the first to begin selling an all-electric car, the EV1, to California buyers. The all-electric cars introduced so far have been limited by low range, long recharges, and weak consumer interest.
Engines that run on hydrogen have been tested. Hydrogen combustion produces only a trace of harmful emissions, no carbon dioxide, and a water-vapor by-product. However, technical problems related to the gas’s density and flammability remain to be solved.

Diesel engines burn fuel more efficiently, and produce fewer pollutants, but they are noisy. Popular in trucks and heavy vehicles, diesel engines are only a small portion of the automobile market. A redesigned, quieter diesel engine introduced by Volkswagen in 1996 may pave the way for more diesels, and less pollution, in passenger cars.

While some developers searched for additional alternatives, others investigated ways to combine electricity with liquid fuels to produce low-emissions power systems. Two automobiles with such hybrid engines, the Toyota Prius and the Honda Insight, became available in the late 1990s. Prius hit automobile showrooms in Japan in 1997, selling 30,000 models in its first two years of production. The Prius became available for sale in North America in 2000. The Honda Insight debuted in North America in late 1999. Both vehicles, known as hybrid electric vehicles (HEVs), promised to double the fuel efficiency of conventional gasoline-powered cars while significantly reducing toxic emissions.

Computer control of automobile systems increased dramatically during the 1990s. The central processing unit (CPU) in modern engines manages overall engine performance. Microprocessors regulating other systems share data with the CPU. Computers manage fuel and air mixture ratios, ignition timing, and exhaust-emission levels. They adjust the antilock braking and traction control systems. In many models, computers also control the air conditioning and heating, the sound system, and the information displayed in the vehicle’s dashboard.

Expanded use of computer technology, development of stronger and lighter materials, and research on pollution control will produce better, “smarter” automobiles. In the 1980s the notion that a car would “talk” to its driver was science fiction; by the 1990s it had become reality.

Onboard navigation was one of the new automotive technologies in the 1990s. By using the satellite-aided global positioning system (GPS), a computer in the automobile can pinpoint the vehicle’s location within a few meters. The onboard navigation system uses an electronic compass, digitized maps, and a display screen showing where the vehicle is relative to the destination the driver wants to reach. After being told the destination, the computer locates it and directs the driver to it, offering alternative routes if needed.

Some cars now come equipped with GPS locator beacons, enabling a GPS system operator to locate the vehicle, map its location, and if necessary, direct repair or emergency workers to the scene.

Cars equipped with computers and cellular telephones can link to the Internet to obtain constantly updated traffic reports, weather information, route directions, and other data. Future built-in computer systems may be used to automatically obtain business information over the Internet and manage personal affairs while the vehicle’s owner is driving.

During the 1980s and 1990s, manufacturers trimmed 450 kg (1,000 lb) from the weight of the typical car by making cars smaller. Less weight, coupled with more efficient engines, doubled the gas mileage obtained by the average new car between 1974 and 1995. Further reductions in vehicle size are not practical, so the emphasis has shifted to using lighter materials, such as plastics, aluminum alloys, and carbon composites, in the engine and the rest of the vehicle.

Looking ahead, engineers are devising ways to reduce driver errors and poor driving habits. Systems already exist in some locales to prevent intoxicated drivers from starting their vehicles. The technology may be expanded to new vehicles. Anticollision systems with sensors and warning signals are being developed. In some, the car’s brakes automatically slow the vehicle if it is following another vehicle too closely. New infrared sensors or radar systems may warn drivers when another vehicle is in their “blind spot.”

Catalytic converters work only when they are warm, so most of the pollution they emit occurs in the first few minutes of operation. Engineers are working on ways to keep the converters warm for longer periods between drives, or heat the converters more rapidly.