Patent ID: 6651601
Filing Date: 2003-11-25
Classification: F01L,F02D,F02N,Y02T

Abstract:
A method of cranking and starting a multi-cylinder internal combustion engine at an engine temperature that is substantially below a range of engine operating temperatures within which engine operation will eventually stabilize after the engine has been running for an amount of time sufficient to bring its temperature within that temperature range, the engine having a kinematic mechanism, including pistons that reciprocate within the cylinders, through which energy of combustion occurring within the cylinders is converted to a torque output, and a variable valve actuation mechanism for varying the opening and closing times of intake and exhaust valves that control flow between the cylinders and the respective intake and exhaust systems, the method comprising:a) cranking the engine while not fueling the cylinders and while operating the variable valve actuation mechanism to cause the pistons in at least some of the cylinders to operate at an initial effective compression ratio for initial cranking that is less than an effective compression ratio for running when the engine is eventually fueled and runs under its own power; b) then, while continuing not fueling the cylinders, operating the variable valve actuation mechanism to cause the pistons in those cylinders that are operating at the initial effective compression ratio to draw charge air through a respective intake valve and compress the drawn charges to an increased effective compression ratio that is greater than the initial effective compression ratio and to exhaust the compressed charges through a respective exhaust valve into the exhaust system; c) then operating the variable valve actuation mechanism to cause the pistons in those cylinders to continue operating at the increased effective compression ratio while commencing to draw a portion of their charges from the exhaust system through the respective exhaust valve; and d) then commencing the fueling of less than all of the cylinders while operating the variable valve actuation mechanism to operate the intake and exhaust valves of the cylinders being fueled to cause the engine to start running under its own power.