Drive the Wave
Turbochargers give hot rods screeching-fast acceleration, using the force of exhaust gases to spin a turbine and compress air flowing into combustion chambers. But there’s a slight lag after you hit the gas, and it gets worse as the engine gets smaller, making the technology impractical for economy cars. Work at the Swiss Federal Institute of Technology in Zrich has yielded a turbocharger variant without this problem. The “pressure wave supercharger” eliminates mechanical steps; the exhaust directly compresses clean intake air in rotating chambers. Early versions proved difficult to control, with exhaust tending to mix with the intake air. To prevent this, mechanical engineer Lino Guzzella’s team uses sensors and actuators that continually alter rotation speed and adjust airflow. Guzzella says the device could enable a peppy car that gets 28 kilometers per liter in city driving, and could reach market within three years.