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Herb Chambers Tech Snapshot Features Prius Doe


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Herb Chambers Tech Snapshot Features Prius Doe

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Herb Chambers Tech Snapshot Features Prius Doe

  1. 1. An introduction by the U.S. Department of Energy to commercially available advanced vehicle technologies OFFICE AND OF ENERGY EFFICIENCY RENEWABLE ENERGY featuring the Toyota Prius What’s Inside... What Is a Hybrid Electric Vehicle? Why the Prius? How Does the Prius Compare with Conventional Vehicles?
  2. 2. U.S. Department of Energy Technology Snapshot — Featuring the Toyota Prius Welcome to the Clean Cities Advanced Vehicle Information Series Dear Reader, What Is a Hybrid Electric Vehicle? A hybrid is any vehicle that uses two or more sources of Twenty-first century transportation is not just power — in today’s HEVs, the two sources are electricity a vision for the future — it’s here today. Clean, fuel-efficient hybrid electric vehicles (HEVs) (from batteries) and mechanical power (from a small are now available, joining the alternative fuel internal combustion engine). HEVs can offer the very low vehicles already on the road. You may have seen emissions of electric vehicles with the power and range of HEVs in the news, at your local dealership, and gasoline vehicles. They also offer up to 30 more miles per even in your neighborhood. This brochure is the gallon, perform as well as or better than, and are just as safe first of the U.S. Department of Energy’s (DOE’s) as any comparable gasoline-powered car — and they never Technology Snapshots, a suite of publications in have to be plugged in for recharging. Widespread use of the Clean Cities Advanced Vehicle Information HEVs would help reduce our nation’s growing dependence Series that is designed to introduce the latest on foreign oil and cut greenhouse gas emissions by one-third commercially available vehicle technologies to to one-half. consumers across the country. Each Snapshot features a different vehicle and offers an objec- tive, “plain English” explanation of how it works How Do HEVs Work? and how it differs from conventional vehicles. Hybrids can offer tremendous fuel economy and emissions The web sites listed on the back cover of this benefits because they operate differently than conventional brochure provide additional information about gasoline-fueled vehicles. advanced transportation technology programs. Gasoline Vehicle: The heat energy obtained by burning Although nothing can compare to sitting behind gasoline powers the engine, which drives the transmission the wheel, each Snapshot gives you a feel for the that turns the wheels. featured vehicle by highlighting performance, vehicle safety, and the benefits the new tech- Electric Vehicle: A set of batteries provides electricity to a nology delivers to you and your community. Are motor, which drives the wheels. you ready to drive a cleaner, “greener” and more fuel-efficient vehicle? Hybrid Electric Vehicle: Not all hybrids are alike. There are many ways to combine the engine, motor/generator, and battery. Three basic hybrid configurations are the series, parallel, and split (or through-the-road) designs. Thomas J. Gross Series. The engine never directly powers the car. Instead, Deputy Assistant Secretary the engine drives the generator, and the generator can for Transportation Technologies either charge the batteries or power an electric motor that Energy Efficiency and Renewable Energy drives the wheels. U.S. Department of Energy Parallel. The engine connects to the transmission, as do the batteries and the electric motor. So both the engine and the generator/motor can supply power to the wheels, switching back and forth as driving conditions vary. Split. The engine drives one axle and the electric motor drives the other. There is no connection between the engine and the electric components except “through the road.” 2
  3. 3. U.S. Department of Energy Technology Snapshot — Featuring the Toyota Prius Introducing the Toyota Prius A New Type of Car… …That Drives Like Any Toyota’s Prius combines features of Other Car… both a “series” and “parallel” hybrid The Prius means more than just electric vehicle, and it is the world’s impressive fuel economy and lower first mass-produced HEV. The Prius emissions. It is a real car that does HEVs Ñ Out of the Lab is a breakthrough in many ways, not have to be “plugged in” or fed and onto the Road combining an efficient gasoline- expensive or hard-to-find fuels. It fueled internal combustion engine drives and accelerates like other What started out as a short-term solu- with a clean, quiet electric motor gasoline-powered vehicles, and tion to extend the range of electric cars powered by a battery. Like other it feels like a comfortable five- HEVs, the Prius has many innovative may turn out to be one of the best passenger sedan. features: options for increasing fuel economy and 8Regenerative braking: The motor …Only Better. cutting greenhouse gas emissions on recovers energy from the brakes Toyota’s claims for the Prius are American roads. When automakers when they slow down or stop the supported by independent labora- installed an onboard generator powered vehicle and uses it to recharge tory testing by both DOE and the battery. by an internal combustion engine in an the U.S. Environmental Protection electric car to make the car capable of 8Lighter, smaller engine: To Agency (EPA). improve efficiency, the Prius longer trips, many viewed it as a tempo- Hybrids may be the cars that engine is sized to accommodate convince the American public that rary measure until better batteries were its average power load, not its advanced technology can be both developed. But HEVs caught on in the peak load. Most gasoline engines affordable and convenient. The next auto industry and, after 20 years of are sized for peak power require- few pages offer more details on the ments, yet most drivers need study, a new generation of hybrids is technology used in these vehicles peak power only 1% of the time. and illustrate how HEVs can deliver taking center stage in the quest for 8Better fuel efficiency: The Prius a cleaner, comfortable drive today. cleaner, more efficient cars and trucks. consumes less fuel than vehicles powered by gasoline alone — partly because the engine is turned off when it’s not needed. Conventional gasoline engines Engine Power to W The Toyot a (THS) (left Hybrid System heels run constantly, regardless of ) Power to G of both th combines feature power requirements. enerator e series a s systems nd paralle (d l The key to escribed opposite). 8Lower emissions: The Prius Generator In Parallel t electronic he THS is an ally contro reduces regulated tailpipe splitter t lled power ha Motor from the t directs power en emissions by up to 90% and wheels an gine to both the d the gen greenhouse gas emissions by Compare erator. Batteries th conventio e THS to a about 50% compared with Tier 2 powertrain nal gasolin e engine Mechanica standards. Electrical l Power few more (below); it has a Power componen uses them ts, more effic but it 8More aerodynamic: The iently. streamlined Prius exterior (0.29 Rear Whee Engine l coefficient of drag) reduces drag by about 14% compared with Transmiss io Drive Shaft n the typical family sedan. 3
  4. 4. U.S. Department of Energy Technology Snapshot — Featuring the Toyota Prius Focus on Technology Prius Engine Helps Recharge THS Transmission Provides The result is a quiet and seamless system — in fact, the only way the Battery Seamless Shifting to know what mode the car is Why doesn’t the Prius ever need The THS transmis- operating in is by checking the to be plugged in for recharging? sion is not a liquid crystal display (LCD) on Because the car recharges its conventional the dashboard. batteries primarily by using its own automatic gasoline engine, in addition to transmission. Innovative Battery Holds a regenerative braking. Some of the There is only power from the engine is “split off” one gear set, Bigger Charge and stored in the car’s battery pack. with no clutch, The battery pack in the Prius is a This “self-charging” system greatly starter, alternator, or torque nickel-metal hydride (NiMH) pack enhances driving range — to more converter. The system fluidly adjusts that operates at 274 volts. The Prius than 600 miles on a tank of gas in the operation of the gasoline engine, features a prismatic battery, in the city. generator, and electric motor to which the positive and negative match driving conditions. The key plates are stacked rather than rolled Prius Constantly “Talks” to this system is a planetary gear (as in a typical cylindrical battery). power-split device that allocates The resulting surface area is larger, to Itself power from the gasoline engine to so the battery delivers more power The Prius has an electronic control both the final drive and the gener- and is more durable. system that “talks” to the car’s key ator. The generator produces the components and ensures that the electrical power that is used to car always operates in its most recharge the high-voltage battery efficient mode — for lower fuel pack and to power the electric consumption and power output that motor. The generator also functions instantly adjusts to driving condi- as a starter for the gasoline engine tions. The engine even shuts off — no other starter is needed. when it isn’t needed for acceleration or to recharge the battery. When engine demand is low, such During normal travel, the gasoline as when starting, traveling at a engine engages as needed to light load, or stopping, the Prius (1) drive the wheels and/or is driven only by its electric (2) recharge the battery. motor, using battery power. Key: Battery Pack Inverter Electric Motor Engine 4 Generator
  5. 5. U.S. Department of Energy Technology Snapshot — Featuring the Toyota Prius Inverter Extends Battery Life An inverter changes the battery’s DC power into AC power for use by the Technical Specifications electric motor, and it also changes Powertrain: Toyota Hybrid System (THS), including: Fuel tank: 11.9 gallons the generator’s AC power into DC 8Gasoline engine: 1.5-L, 16-valve, 4-cylinder, Max. range: 619 mi (city)/ power to recharge the battery pack. cast-aluminum block and head, EFI Atkinson- 535 mi (highway)** cycle VVTi (Variable Valve Timing with Passengers: 5 It regulates the power from regener- intelligence), 13:0:1 compression ratio, 70 hp ative braking and extends battery at 4,500 rpm, 82 lb-ft of torque at 4,200 rpm Length: 169.6 in. life by always maintaining the 8Electric motor: Three-phase AC permanent Width: 66.7 in. proper charge. magnet with peak power of 33 kW/44 hp Height: 57.6 in. at 1,040–5,600 rpm, peak torque of 350.0 N-m/258 lb/ft (0–400 rpm) Wheelbase: 100.4 in. Braking System Helps 8Battery: Sealed nickel-metal hydride battery, Weight: 2,765 lb Improve Fuel Economy 274 volts Cargo: 10 ft3 Transmission: Electronically controlled, Braking: Front disc/rear drum (hydraulic When a driver slows down or steps on continuously variable, with power assist) with integrated the brake in the Prius, the regenerative power-split transaxle regenerative system, ABS braking system converts kinetic energy Max. speed: 100 mph Steering: Rack and pinion, with power assist from the motion of the wheels — Acceleration: 0–60 miles per hour in Turning circle: 31.6 ft normally dissipated as heat in the 12.7 seconds brakes — into electric current to help Suspension: Front: MacPherson strut Fuel efficiency: 52 mpg city/45 mpg highway* Rear: torsion beam recharge the battery. About 20% of Coefficient of drag: 0.29 (drag for 5-passenger car the total energy consumed by the is typically 0.355) * EPA label values Prius comes from regenerative Emissions: Meets California Super Ultra ** Based on 11.9-gal fuel tank and 52 mpg city/ braking, which contributes to the Low Emissions Vehicle (SULEV) 45 mpg highway. car’s excellent fuel economy. standards At full acceleration, the battery When decelerating or braking, the The engine shuts off when the car is adds its power to the mix, which regenerative braking system acts idling or if engine demand is low. The provides a very smooth and as a generator to help recharge gasoline engine runs only as needed to powerful response. the battery. recharge the battery or run the air conditioner, which is why the Prius never has to be plugged in for recharging. 5
  6. 6. U.S. Department of Energy Technology Snapshot — Featuring the Toyota Prius Independently Tested by the DOE and EPA DOE Focuses on Argonne researchers focused primarily on the powertrain control Prius Performance and energy management systems, Starting in March 1999, DOE measuring numerous system func- conducted independent testing tions: engine speed and mass airflow; of the Prius at Argonne National exhaust gas and coolant temperature; Laboratory and the National generator and motor speeds; Renewable Energy Laboratory accumulated ampere-hours; battery (NREL). The testing goals included voltage; battery, motor, and gener- determining the operating ator current; vehicle speed; carbon performance of the hybrid monoxide (CO), nitrogen oxides technology and collecting data (NOx), and hydrocarbon (HC) to determine the overall energy emissions; and fuel efficiency. management performance of the NREL researchers focused on battery entire vehicle and its individual thermal management performance. components, including the batteries. Work at DOE laboratories included devel- oping an engine map — the set of data that relates an engine’s fuel consump- tion, power output, and emissions; examining the vehicle’s hybrid control strategy; collecting data on powertrain EPA Takes a Closeup operation; outfitting a car for mobile testing during on-road city and highway Look at THS driving; and extensive battery testing. In 1998, the U.S. Environmental Protection Agency evaluated the Prius THS technology Why Drive a Hybrid Air Emissions over two test sequences involving the Growing scientific evidence suggests Federal Urban Dynamometer Driving Electric Vehicle? that greenhouse gas emissions Schedule and the Highway Fuel Economy As the information in this brochure illustrates, the Prius could contribute to a change in the Test (HFET). and other HEVs are mechanically innovative, sophisticated earth's climate — and transpor- vehicles. Many people might ask why they should drive The results of these tests are provided in tation, specifically the combustion these technological marvels when their current car does the EPA report “Evaluation of a Toyota of fossil fuels in our vehicles, everything they want it to do. The two best reasons are Prius Hybrid System,” EPA420-R-98-006, accounts for a large portion of (1) to improve mileage and (2) to reduce emissions. greenhouse gases. Moreover, EPA August 1998, on the EPA website: The Outlook on Oil considers a number of other pollu- tants in vehicle emissions to be Most people dislike having to pay $20 or $30 or more for harmful to public health and the a tank of gas. Yet, the United States depends on petroleum environment. Despite the substan- for nearly 95% of its transportation energy — about 8 tial reductions in individual vehicle million barrels per day of petroleum products are used to emissions over the last few decades, fuel light trucks and cars. More than half of our petroleum the millions of vehicles on our is imported, and this percentage is growing, which is why roads — which burn thousands oil imports represent one of the largest components of the of gallons of petroleum every U.S. trade deficit. And the demand for oil used for trans- second — account for a third of portation will grow as the number of people and the the country's air emissions. number of miles they drive increase. 6
  7. 7. U.S. Department of Energy Technology Snapshot — Featuring the Toyota Prius Fuel Economy Emissions Comparison New Car Requirements Prius (Actual 2000 Prius 46.0 EPA Test Results) 0.009 SULEV (California's Most Stringent Light- Corolla 31.6 Duty Vehicle Standard 0.02 Starting 2004) TIER 2 (Federal Light-Duty Fleet Camry 25.3 Average Standard 0.07 Starting 2004) 20 25 30 35 40 45 50 0 0.01 0.02 0.03 0.04 0.05 0.06 0.07 0.08 Fuel Economy (miles per gallon) Oxides of Nitrogen (NOx) (grams/mile) Acceleration (0–60 mph) Handling (Slalom) Prius 12.7 Prius 11.5 Corolla 11.4 Corolla 12.1 Camry 12.2 Camry 11.5 9 10 11 12 13 11.0 11.2 11.4 11.6 11.8 12.0 12.2 Time (seconds) Time (seconds) Picture-Perfect Performance The Prius truly appeals to people who want a car with excellent performance that is also friendly to the environment. The "Emissions Comparison" chart above DOE took its testing efforts on the road in illustrates how Prius almost eliminates harmful emissions — it already meets September 2000. At the Route 66 Motor California Super Ultra Low Emission Vehicle (SULEV) standards that take effect in 2004 — without sacrificing performance (see table below). Prius reduces Speedway near Chicago, Argonne engi- hydrocarbon (HC), carbon monoxide (CO), and nitrogen oxides (NOx) emissions neers tested the model year 2001 Prius by up to 90% and carbon dioxide (CO2) and other GHG emissions by up to 50% against a similarly equipped 2001 Toyota relative to those of a comparable gasoline-fueled vehicle. But the vehicle can still handle as well as or better than comparable 5-passenger cars (see slalom and Camry and 2001 Corolla to see how they skid pad test results below), accelerate from 0 to 60 mph in under 13 seconds, compared in terms of fuel economy, accel- and achieve fuel economy as high as 52 miles per gallon. eration, handling, and braking. The results are shown in the charts above and in the Prius Corolla LE Camry LE table at right. On-Road Fuel Economy (mpg) 46.0 31.6 25.3 EPA Fuel Economy (city/highway) (mpg) 52/45 29/33 23/32 Acceleration (sec) 0–60 mph 12.69 11.41 12.15 Slalom (sec) 11.45 12.10 11.46 Skid Pad (G) 0.654 0.667 0.651 Braking (ft from 60–0 mph) 135.1 173.6 * 198.2 Passenger/Luggage Volume (ft3) 89/12 88/12 97/14 *Not equipped with anti-lock brakes. 7
  8. 8. U.S. Department of Energy Technology Snapshot — Featuring the Toyota Prius The U.S. Department of Energy’s mission is to enhance our nation’s energy security, national security, and environmental quality, and to contribute to a better quality of life for all Americans. The widespread availability and use of alternative fuels and clean, energy-efficient, advanced technology vehicles (like those profiled in the Technology Snap- shots) will help reduce U.S. dependence on foreign petroleum and promote clean air and healthier living in communities nationwide. Prius Cleans Up Related Web Sites with 5 Environmental The U.S. Department of Energy’s Office of Transportation Technologies Awards (OTT) develops and promotes advanced transportation and alternative fuel vehicles and technologies. 8United Nations Environmental Protection Award OTT’s Clean Cities Program supports the deployment of alternative fuel 8EPA’s First Annual Global Climate vehicles and supporting infrastructure. Protection Award 8Sierra Club’s “Excellence in OTT’s Hybrid Electric Vehicle Program. Environmental Engineering Award” Related sites from government, educational, commercial, and 8”Clean Car Salute” from the Clean Car organizational sources. Coalition, a group composed of state, regional, and national environmental Toyota Motor Corporation web site. organizations in the U.S. 8Exhibited at the Museum of Modern The web-based version of the DOE/EPA Fuel Economy Guide. Art, “Different Roads: Automobiles for the Next Century” This document highlights work sponsored by agencies of the U.S. Government. Neither the U.S. Government nor any agency thereof, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement, recommendation, or favoring by the U.S. Government or any agency thereof. The views and opinions of authors expressed herein do not necessarily state or reflect those of the U.S. Government or any agency thereof. 8 Publishing services provided by Argonne National Laboratory