Patent ID: 6912458
Filing Date: 2005-06-28
Classification: F02B,F02D,Y02T

Abstract:
1. An engine, comprising: an engine block defining at least one cylinder; a piston slidably disposed within the at least one cylinder; an intake valve moveable between a first position where the intake valve prevents a flow of fluid to the at least one cylinder and a second position where the intake valve allows a flow of fluid to the at least one cylinder; a cam assembly connected to the intake valve to move the intake valve between the first position and the second position; a valve actuator selectively operable to prevent the intake valve from returning to the first position; a sensor operable to sense an operating parameter of the engine; and a controller having a memory adapted to store a first lookup map and a second lookup map, the controller operable to access the first lookup map to determine a desired air-to-fuel ratio when the sensed parameter indicates that the engine is operating at an altitude below a first predetermined value and to access the second lookup map to determine a desired air-to-fuel ratio when the sensed parameter indicates that the engine is operating at an altitude above the first predetermined value, the controller further operable to determine a desired valve actuation period based on the determined air-to-fuel ratio and to prevent the intake valve from returning to the first position until the end of the determined valve actuation period.