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Welcome to the year of the hybrid electric vehicle. Although Toyota's Prius has been commercially available for six years and well over 100 000 of them are on roads from Tokyo to Tucson, 2004 will go down as the year when hybrids came into their own as a full-fledged automotive force. Manufacturers now ignore them only at their peril.
Consider the evidence. First, there's the Prius itself, all new in 2004 and garnering some of the most breathless reviews ever given to a family sedan—a car category that rarely sends reviewers scrambling for rapturous superlatives. Second, this year will finally see multiple manufacturers on several continents offering hybrids in everything from two-seat runabouts to SUVs and pickup trucks. There will be full hybrids along with so-called mild hybrids, which use relatively small electric motor/generators—beefed-up starter motors, really—to provide more modest fuel-economy gains, mainly in stop-and-go traffic. Finally, China's proposal for rigorous fuel-economy standards may leave carmakers little choice but to lean more heavily on hybrid technology as they plan models for a country viewed as the world's largest and most promising new car market.
Meanwhile, every automaker's R&D division is experimenting with hydrogen and fuel-cell technologies, though production passenger vehicles are at least a decade away. Ford Motor Co., Dearborn, Mich., and DaimlerChrysler AG, Stuttgart, Germany, are now testing the first fruits of their joint investment in fuel-cell pioneer Ballard Power Systems Inc. of Burnaby, B.C., Canada. Ford is about to put a fleet of hydrogen fuel-cell vehicles into use in Vancouver, B.C., Canada, while London took delivery of three fuel-cell-powered Mercedes-Benz Citaro buses and Perth, Australia, will soon follow suit.
Manufacturers are now struggling with basic fuel-cell engineering issues, like the 2 to 30 seconds of "light-up time" needed for the stack to deliver full power. Parking a fuel-cell car in subfreezing temperatures would also be a problem, because the deionized water in fuel-cell membranes would turn into ice. In the broader picture, though, the long-term success of a "hydrogen economy" in reducing greenhouse gases will depend greatly on the energy sources used to generate the hydrogen in the first place.
The 10 vehicles here not only pioneer new electrotechnologies across the spectrum of automotive design, they also point the way forward. Most are production vehicles, available for sale this year or next somewhere in the world. From hybrid power systems to 42-volt electric components, these cars prove that technical advances lead the march of automotive progress. And that's as it should be.
CONCEPT HYUNDAI HCD-8 SPORTS TOURER
LEDs light the way
FROM THEIR FIRST APPEARANCE in instruments and consumer gadgets, light-emitting diodes (LEDs) have steadily migrated into larger applications and harsher environments—traffic and crosswalk signals, video billboards, flashlights, and more.
They've also carved out a growing market in automobiles: LEDs are already used in taillights, high-mounted brake lights, turn-indicator lights, and dashboard and interior lighting. Indeed, automotive-lighting manufacturer Koito Manufacturing Co., Tokyo, expects LED taillights to represent 80 percent of its sales by 2006.
The next big automotive opportunity, analysts agree, is headlights.
Hyundai's HCD-8is one of a handful of concept cars unveiled in recent years that put high-brightness white LEDs in front. The low, sleek, slippery coupe was introduced in January at the 2004 North American International Auto Show in Detroit, Mich., and is the first vehicle to emerge from Hyundai's brand-new Design & Technical Center in Irvine, Calif. A supercharged 2.7-liter V6 engine and a six-speed manual gearbox provide the gusto, as does a height-adjustable air suspension that can be raised 100 millimeters for better clearance over rough roads.
There are several different ways to get white light out of an LED. One combines red, blue, and green devices. But Osram Opto Semiconductors GmbH of Regensburg, Germany, which teamed with Light Prescriptions Innovators LLC of Irvine, Calif., to provide the HCD-8's lighting, took a simpler tack. It put a blue LED behind a phosphor that emits yellow light when stimulated by the blue. Together, the blue and yellow rays make white. Osram says its technology is less expensive than the three-chip systems, which can cost more than 10 times as much as incandescents.
A big challenge in LED lighting is creating a sufficiently powerful beam in the appropriate pattern. The 2002 Ford Mighty F-350 Tonka concept truck, for example, required 40 high-intensity white LEDs—each separately aimed—to create a single low- and high-beam headlight.
Analysts expect the costs to come down and LED headlights to start appearing on production cars between 2005 and 2008. The advantages are overwhelming: LEDs consume half the power of halogen bulbs, or one-tenth that of ordinary incandescent bulbs. They switch on in nanoseconds, rather than milliseconds. They are much cooler and can be brighter as well. Their life span exceeds 10 000 hours, and the lack of a fragile filament lets them withstand serious abuse. Designers gain greater packaging flexibility, with less depth needed for reflectors and bulb sockets behind the lens. And the advent of 42-volt auto electrical systems will make LEDs even more compelling, because when they are connected in series they are well suited to higher voltages.
Dynamic roll-stability control in a feedback loop
VOLVO CAME LATE TO THE SUV PARTY; its first entry in the category, the XC90, debuted in the 2003 model year. Its proprietary Roll Stability Control (RSC) helps drivers maintain control of the SUV during extreme maneuvers that might otherwise flip this tall vehicle. The Volvo/Ford development team for RSC drew on previous experience with AdvanceTrac, a yaw-control system introduced on the 2000 Jaguar S-type and Lincoln LS. That system monitors steering-wheel angle, throttle position, and wheel speed, applying anti-lock brakes and reducing the throttle if necessary to keep the car from entering a skid.
The RSC software is integrated into the XC90's brake controller, which includes Volvo's Electronic Stability Control system. A gyroscopic sensor continuously monitors the vehicle's body-roll rate and feeds this data into the system's control algorithm. The roll-rate signal, coupled with proprietary vehicle modeling techniques, lets the RSC constantly estimate vehicle motion and attitude.
If the system calculates that the vehicle is dangerously close to flipping over, it preemptively adjusts brake torque at specific wheels to reduce cornering forces and the overall roll moment. It can also reduce engine power, while a separate system evaluates whether to trigger the air bags.
The big challenge for the system's designers was improving stability across the huge variety of operating conditions that an SUV may encounter, especially when used off-road, while limiting "false-alarm" activations. Ford has many issued and pending patents on the RSC technology and is already offering to license it to other automakers. It now offers the system on the 2004 Lincoln Navigator and Aviator SUVs and plans to add RSC to other vehicles in coming years.
Active steering makes ultimate driving experiences safer
BMW HAS BECOME THE FIRST manufacturer to offer an electronic "active steering" system. Introduced as an option on the 2004 5-series sedanand 6-series coupe, it acts in two ways. It works with BMW's Servotronic variable-effort power-steering system to vary the actual steering ratio—or number of turns of the steering wheel to move the front wheels from lock to lock—based on speed and other factors. But in emergency situations, it can actively intervene to steer the car if the driver's actions are making things worse.
This is not, however, a full steer-by-wire system, in which electric motors move the control arms with no direct mechanical connection to the steering wheel. Rather, the system interposes a planetary gear set, driven by an electric motor, between the steering wheel and the shaft that turns the rack. This rack moves control arms that pivot the front wheels away from the straight-ahead position. A system-control module processes both driver input and data from vehicle sensors, varying the actions of the steering rack. At low and medium speeds, steering ratio tightens to as little as 10:1, so the car is more agile in traffic or when parking. In this case, a small movement of the wheel turns the front wheels through a relatively large angle, reducing driver effort. At higher speeds, the ratio increases to as much as 20:1 for improved directional stability. During high-speed cornering, the system stiffens the steering as well.
Data from the car's stability control system—including road speed, body roll, yaw, braking input, and wheel traction—are fed continuously into the controller along with steering inputs. If the control algorithms indicate that a driver's steering action could cause the rear wheels to lose adhesion, the controller overrides or modulates that input. It can turn the front wheels up to 2.5 degrees in the opposite direction to avert a potential skid.
LEXUS RX 400H
V8 power, SUV roominess, hybrid economy
THIS FALL, TOYOTA will offer a hybrid-electric version of its Lexus RX SUV, the most popular Lexus in the U.S. market. The company showed the concept vehicle for this model, known as the Lexus SU-HV1, at several auto shows during 2003.
The new Lexus RX 400H will use Toyota's Hybrid Synergy Drive [see Toyota Prius] combined with a 3.3-liter V6 engine running on the Atkinson cycle, which improves efficiency by simulating different lengths for the intake and power strokes. The gasoline engine will generate at least 150 kilowatts (200 horsepower), compared with 172 kW from the standard Toyota Lexus RX 330's conventional 3.3-L engine. The hybrid's 500-volt power system will drive a front electric motor of at least 120 kW.
The Lexus will offer all-wheel drive through a second electric motor of at least 50 kW that drives the rear wheels—unlike Ford's Escape Hybrid, which uses a mechanical transaxle to drive all four wheels. The Lexus setup echoes that of the E-Four electric four-wheel-drive system offered in Japan since 2001 in Toyota's Estima hybrid minivan. That system coordinates both electric power distribution among all four wheels and power recovery during regenerative braking.
The RX 400H will be the first SUV to power the rear wheels solely with electricity for all-wheel drive. While the demands on all-wheel-drive systems in SUVs exceed those on urban delivery vans like the Estima, owners of luxury SUVs ("soft-roaders") rarely use their vehicles off-road. For them, all-wheel drive simply improves bad-weather traction. As one industry observer puts it, with a barely perceptible hint of disdain, "Lexus owners never do anything that might scratch the paint."
The RX 400H will be followed by hybrid versions of the Toyota Highlander in January 2005 and, if industry rumor can be trusted, of the Sienna minivan.
Bigger, faster—and even stingier with fuel
TOYOTA'S 2004 PRIUS, which benefits from a major redesign, outdoes its predecessor in every measurable way. It has higher-voltage electrics—500 volts rather than 288—and a more powerful electric motor, at 50 kilowatts rather than 30. The car has grown to a midsize from a compact, and is reasonably aerodynamic, with a coefficient of drag of 0.26. Acceleration from zero to 60 mph (97 km/h) has improved by a full two seconds, to 10.5 seconds—about the same as a Chrysler PT Cruiser with the standard engine and automatic transmission. Even with all these performance enhancements, the Prius's fuel economy has also improved, to 4.28 L/100 km (55 mpg) from 4.90 L/100 km (48 mpg) in the U.S. Environmental Protection Agency's combined city/highway cycle.
The Prius's great breakthrough is a system, called the Hybrid Synergy Drive, for seamlessly diverting power from the engine and motor/generators to where it's needed, whether it's the motors, the battery pack, or some combination. The key elements in the powertrain are two motor/generators, which, depending on conditions, are powered by a 202-V, 1.3-kilowatthour battery pack and a 1.5-liter gasoline engine that puts out 57 kW (76 horsepower).
GO WITH THE FLOW
The Prius's integration of electric and gasoline power is revealed only by the dashboard power-delivery monitor, which shows what system is moving the vehicle.
The main motor/generator is a 50-kW (67-hp) synchronous unit that drives the front wheels through a reduction gear. The secondary motor/generator has many functions: recharging the nickelmetal hydride batteries, supplementing the power from the main electric motor, and starting and stopping the gasoline engine in traffic to save fuel.
The heart of the Hybrid Synergy Drive system is a planetary gear set, in which a central gear (the "sun") connects to the drive shaft of the secondary motor/generator. This central gear is surrounded by "planet gears" that are in turn surrounded by a "ring gear" that drives or is driven by the main motor/generator. What the system does, basically, is vary the power split between the primary and secondary motor/generators by altering the speed at which the planet gears spin. Different driving conditions call for more power from the primary motor, to move the car, or more going into the secondary, to charge the batteries. The Hybrid Synergy Drive system quickly adjusts the relative power levels to best suit those conditions—without changing the mechanical load on the gasoline engine. In effect, this arrangement acts as a continuously variable transmission, letting the engine run steadily at its most efficient output regardless of road speed. The Prius hybrid system has been so successful that Nissan has licensed it from Toyota for use in a hybrid version of its Altima sedan for 2006.
The Prius's primary electric motor provides a full 78 percent of the car's total torque of 511 newton-meters (377 pound-feet) at peak output. On electric power alone, the 1310-kilogram Prius can accelerate to 40 mph (64.4 km/h) in 4.9 seconds.
Its urban-cycle fuel usage of 3.92 L/100 km (60 mpg), compared with 4.61 L/100 km (51 mpg) on the highway cycle, is characteristic of hybrids: fuel-economy gains are highest in urban driving with lots of stop-start cycles, when they can run on battery power alone.
Meanwhile, the car offers a full complement of power accessories, including Toyota's first electric air conditioner, driven by an inverter. Toyota projects global sales of 76 000 this year, roughly two-thirds of that in North America.
FORD ESCAPE HYBRID
A no-compromises hybrid sport utility vehicle
THIS COMING JULY, FORD will start manufacturing the hybrid version of its popular Escape sport utility vehicle (SUV). At the company's plant in Claycomo, Mo., hybrid and nonhybrid Escapes will be put together side by side on the same production line. It's a big deal: the Escape will be the first mass-produced hybrid SUV, as well as the first hybrid built in North America.
The truck's 2.3-liter gasoline engine operates on the Atkinson, or five-stroke, cycle, in which valve timing simulates a cycle in which the piston moves through strokes of different lengths. The advantage is greater efficiency: by changing the stroke length, you can let the combusting fuel-air mixture expand to a greater volume on the power stroke than it originally occupied on the intake stroke. Meanwhile, the compression ratio stays constant, so the engine extracts more energy from the fuel than is possible with a conventional, four-stroke Otto-cycle engine, with its constant stroke lengths. The Atkinson is becoming the engine of choice for hybrids because its lower torque at low engine speed is an ideal match for the high power immediately available from a hybrid's electric motors when starting from rest.
A compact hybrid transaxle moves power from the engine and the 65-kilowatt electric motor among the four drive wheels when the truck is in all-wheel drive. To eliminate high-voltage wires and connectors to and from the motors, Ford mounted the power electronics and capacitor directly on the transmission in a box only slightly larger than a cigarette pack (75 by 75 by 16 millimeters).
This hybrid drive system was developed jointly by Ford, Volvo, and Aisin Industry Co. of Ohbu City, Japan, a company tightly affiliated with Toyota.
Ford claims the Escape Hybrid's acceleration will equal or beat that of the 150-kW (201-horsepower) V6 nonhybrid equivalent. Fuel usage is projected at 50 percent of the V6 Escape's, or better than 6 L/100 km (roughly 40 mpg) in city driving. Similar hybrid-electric powertrains will be used in other Ford vehicles, including the Futura sedan, to be introduced in 2005.
CONCEPT FORD HYDROGEN HYBRID RESEARCH VEHICLE
Testing hydrogen in old-fashioned internal combustion
HYDROGEN-FUEL-CELL CARS get all the attention these days, but in the near future, it's a better bet that hydrogen will power vehicles using a much less exotic technology: the ubiquitous internal combustion engine. This bridging strategy could stimulate development of the necessary hydrogen infrastructure and give automakers valuable experience with the complexities of onboard hydrogen fuel storage and safety. And unlike hydrogen fuel cells, hydrogen-powered internal combustion engines start in all weather and require no warm-up.
Ford's Hydrogen Hybrid Research Vehicle, or H2RV, is a modified Focus wagon. It combines a hydrogen-fueled, 2.3-liter, four-cylinder, 82-kilowatt (110-horsepower) engine, supercharged and intercooled, with Ford's new Modular Hybrid Transmission System. This system combines an upgraded four-speed automatic transmission and a 300-volt electric motor generating 25 kW (33 hp). The fact that this combination takes up no more space than Ford's ordinary CD4E automatic transmission will let Ford engineers integrate it into many vehicles, says Tom Watson, manager of powertrain engineering for the vehicle.
Ford evaluated a bunch of hydrogen storage systems, including liquefied hydrogen and fuel storage cells using sodium borohydride, a complex metal hydride, as well as other metal hydrides. In the end, it opted to store compressed gaseous hydrogen at 340 atmospheres in an aluminum fuel tank strengthened with carbon fibers.
Two H2RVs have now covered over 16 000 kilometers around Detroit. The car's current range is roughly 200 km (125 miles) from 2.8 kilograms of hydrogen. Its 11-second acceleration from zero to 60 mph (97 km/h) keeps up with traffic.
HONDA INSPIRE AND ACCORD
A lane-keeping option for drivers in Japan
ALONG WITH THE CIVIC, the Inspireand Accord are Honda's volume offerings in its three main markets: Japan, Europe, and the United States. Known by different names in different markets, these cars offer the optional Lane-Keeping Assist System (LKAS) only in Japan.
The Honda system is a step beyond lane-departure warning systems now offered by other manufacturers, mainly for trucks and other commercial vehicles. A lane-departure system alerts the driver that the vehicle is drifting toward the edge of the lane by playing a rumble-strip noise through the speakers. If the driver fails to respond, the system progresses to generating a vibration in the steering wheel that mimics the feel of passing over road-edge rumble strips.
Now, suppose the driver still doesn't rouse from blissful slumber, or look up from the hot coffee that has tumbled into his groin. That's when the Honda LKAS shows how it isn't just another lane-departure system: it actually takes over the steering of the car, at least momentarily, to keep the vehicle in its lane—something no other such system now on the market can do.
Part of the Honda Intelligent Driver Support system, the LKAS identifies the boundaries of the vehicle lane by processing images from a camera mounted in the windshield. The system operates on straight roads and on curves with a radius of at least 230 meters, from vehicle speeds of 65 to 100 km/h.
A footnote: in the North American market, Iteris Inc. of Anaheim, Calif., has announced that its AutoVue Lane Departure Warning system will be offered on a 2005 model, though the company will not announce the manufacturer and vehicle until later this year. Unlike the Honda system, the Iteris offering won't be able to steer the vehicle, and it isn't the first such system offered for passenger cars—Mitsubishi had one as early as 1999 on its limited-production Proudia luxury sedan. But it will be the first offered for passenger vehicles in the U.S. market. From more variable and rougher surfaces to specific conditions like raised "Bott's Dots" reflective lane-edge markers, North American roads are considered the most challenging for writers of lane-departure software.
CHEVROLET SILVERADO HYBRID
A pickup truck offering 110-volt alternating current
AS HYBRID ELECTRIC CARS PROLIFERATE, General Motors Corp. has decided on a different tack. It is concentrating on mild hybrids and trucks, which offer modest fuel-economy gains with a simpler drivetrain than full hybrids. Its first offering is a mild hybrid version of the Extended Cab Silverado, which was made available to commercial and fleet customers early this year. Individual customers will be able to buy the truck in the late fall.
GM says it chose the truck because it sells more full-size pickups than any other vehicle—about 700 000 a year—and because hybrid systems save a greater volume of fuel in larger, heavier vehicles than they do in small, light ones.
The Silverado Hybridhas a 295-horsepower Vortec 5.3-liter V8 engine coupled to a compact 14-kilowatt electric motor and a 42-volt lead acid battery pack (three 14-V batteries located under the rear seat). An integrated starter/generator replaces the standard starter and the alternator, recharging the battery through regenerative braking as well. When the truck idles, the engine is shut off and accessories are run on battery power. GM says fuel economy is improved by 10 to 12 percent.
A power converter that uses the same coolant as the engine converts 42-V dc from the batteries to 14-V dc—to power the truck's accessories—and also to 110-V ac. Builders and campers alike will have easy access to 110-V, 20-ampere ac power with ground-fault protection. They can plug into two North American standard three-point electric outlets in the cab and another two in the pickup bed. The 42-V battery can supply 2.4 kW of power at 20 A, enough to run hand tools, or charge their batteries, or keep a few household appliances going in a beautiful spot in the middle of nowhere.
Because emissions from stand-alone portable generators are not regulated by the U.S. Environmental Protection Agency, this 110-V capability makes the entire truck a relatively clean mobile generator. The generator button on the dash starts the engine and the 110-V power. With a full tank of gas, the generator runs for 32 hours, shutting itself down when there are about 7.5 L left—enough, with any luck, to get you to a gas station. The hybrid package costs about US $2500, boosting the price of the truck by less than 10 percent.
This is not GM's only hybrid system under development: in 2006, the Saturn Vue sport utility vehicle will get what the carmaker calls a Belt Alternator Starter hybrid system coupled to a continuously variable transmission, which is supposed to cut fuel consumption by 12 to 15 percent. GM plans to offer the Chevrolet Malibu sedan with the same system in 2007.
TOYOTA CROWN ROYAL
The world's first 42-volt electrical system in a production car
THE CROWN ROYALis a big Toyota sedan rarely seen outside Japan and the Middle East. But a hybrid variant of the car, introduced in October 2002, offers a feature no other current production car shares: 42-volt electric components. They are the first to use the new standardized 42-V PowerNet electrical architecture being developed internationally to support greater electric loads in future vehicles.
This Crown is a mild hybrid, offering somewhat better fuel economy than a conventional car but not the kind of fuel stinginess associated with a full hybrid. When the vehicle stops, the Toyota Hybrid System-Mild goes into "idle-stop" mode, shutting down the 3-liter in-line six-cylinder gasoline engine. An electric motor bigger than an ordinary starter motor, but not as big as the traction motor in a regular hybrid, accelerates the vehicle from a standing stop while the gas engine is restarted. This small motor also acts as a generator to charge the battery, driven via a belt from an accessory drive on the engine. On deceleration, it captures braking energy and feeds it back into the battery.
Toyota's tests show that in urban duty cycles with heavy stop-and-go traffic, the Crown's idle-stop battery system cuts its fuel usage by about 15 percent.
The higher voltage means lower current, and therefore thinner wiring harnesses than those in standard 12-V systems, which reduces weight and improves fuel economy. But the primary motivation behind the new 42-V standards is the need to accommodate the growing electric load of modern autos, including hybrids. Among the current and future features are stability-control systems, dynamic suspensions, variable valve timing, "drive-by-wire" electric power steering and braking, and adaptive cruise control. With the added demands of lane keeping, collision avoidance, heated windshields, and other power accessories, the vehicle draws so much current that 12-V systems are reaching their limit—as 6-V systems did half a century ago, when General Motors introduced the first 12-V system in 1955.
At the 2003 Tokyo Motor Show, Toyota displayed a concept for a new Crown, expected for the 2005 model year. In the meantime, this low-volume mild hybrid—just 1574 were sold in 2002—is the only car in the world with 42-V components.