Patent ID: 7360523
Filing Date: 2008-04-22
Classification: F01L,F02B,F02D,Y02T

Abstract:
1. Method for operating a multi-cylinder, spark-ignition, direct-injection, four-stroke internal-combustion engine adapted to operate in a controlled auto-ignition mode selectively operative at stoichiometry and lean of stoichiometry, the method comprising: adapting an engine valve actuation system to control engine valve opening and closing; monitoring engine operating conditions; monitoring ambient barometric pressure; operating the engine unthrottled and controlling the engine valve actuation system to effect a negative valve overlap period when the engine operating conditions are within predetermined ranges; injecting a mass of fuel during the negative valve overlap period; and selectively decreasing the magnitude of the negative valve overlap period with decreasing ambient barometric pressure and selectively increasing the magnitude of the negative valve overlap period with increasing ambient barometric pressure.