Patent ID: 6609492
Filing Date: 2003-08-26
Classification: F02B,F02D,Y02T

Abstract:
A method of operating a spark ignition direct injection engine having two groups of cylinders supplied with air by separate manifolds each controlled by a separate throttle, the method comprising:in a lower range of engine output, operating both groups of cylinders in a stratified charge mode with essentially unthrottled intake of air into the cylinders and varying the mass of fuel delivered to the cylinders to control the engine power output; in a higher range of engine output, operating both groups of cylinders in a homogeneous charge mode with partially throttled to unthrottled air flow in a range from intermediate to maximum engine output; and in an intermediate range of engine output, operating one cylinder group in a homogeneous charge mode near maximum output with essentially unthrottled intake air while operating the other cylinder group in a stratified charge mode with essentially unthrottled air intake and varying the mass of fuel delivered to the cylinders of the other group to control the engine power output, whereby the engine is operated over a major portion of the engine output range in an unthrottled condition and with substantial throttling only in a portion of the higher range of engine output.