A Method of Assisting Cold-Starts, Improving Fuel Economy and Reducing Emissions of Engines at Cold Temperatures

A slightly modified thermodynamic cycle for a spark ignition engine is proposed as a means of improving cold starting, warm-up driveability and fuel economy. Tests were conducted on a single cylinder research engine using a modified camshaft to implement the cycle. Substantial improvements in BSFC were obtained not only during the warm-up period but also at normal steady-state temperatures. NO_x, CO and UBHC were simultaneously reduced as well.