Developed by engineers at the Southwest Research Institute, the Parallel Hybrid Electric Combination of Speeds (PECOS) powertrain was tested using federal procedures to emulate highway and city driving. PECOS achieved a fuel economy of 77 mpg for city driving and 82 mpg for highway driving.
The powertrain can accelerate a vehicle with a mass of 1,265 kilograms, an aerodynamic drag coefficient of 0.34, and a frontal area of 2 square meters from 0 to 60 mph in 14.9 seconds.
PECOS conists of 40-kilowatt, 1-liter spark ignitition engine; a 53-kilowatt, permanent-magnet brushless DC motor; a power-splitting planetary gearbox, and a 312-volt lead-acid battery pack.
The gearbox contains one sprag clutch and one wet clutch. The two clutches transition the powertrain from one mode of operation to another, using a fuzzy logic strategy based on road conditions. Four operating modes are possible: a pure electric mode, a battery pack charge mode, a motor-assisted engine mode, and a regenerative braking mode.
PECOS has several advantages over conventional powertrains. It does not require a clutch to launch the vehicle--the motor can spin backward until the drive wheels are engaged. The engine does not require a starter, and no transmission is required except for a differential.
For more information, call 210-522-3965 or visit www.swri.org.
