Swirl control system for varying in-cylinder swirl

Abstract

The swirl control system is provided for varying the swirl of intake air in an internal combustion engine comprising a primary intake air passage for delivering a primary flow of intake air having an initial angular momentum corresponding to a low swirl energy level and a secondary intake air passage connected to the primary passage for directing a secondary air flow at a predetermined flow rate into the primary air flow to form a combined air flow having a combined angular momentum greater than the initial angular momentum of the primary air flow. The secondary air flow enters the primary passage substantially tangential, to the primary air flow so as to substantially avoid destructive interference with the primary air flow thereby minimizing pressure losses in the primary passage. A secondary air flow control valve for controlling the flow of secondary air into the primary passage is operable to vary the combined angular momentum so as to vary the swirl of intake air in the combustion chamber. The low swirl primary passage may be helically-shaped and the secondary passage may include a tubular channel portion either formed integrally with the primary passage or pivotally connected to the primary passage so that movement of the tubular portion varies the angle of the tubular portion with respect to the horizontal plane while maintaining the tangential relationship between the secondary and primary air flows.