Coordinated valve timing and throttle control for controlling intake air

A system for controlling intake air of an engine, the engine having at least one combustion chamber provided with an intake valve together with an intake manifold provided with a throttle valve, wherein an opening and closing timing of the intake valve is adjustable independently from a crankshaft, the system comprising:

• a control unit configured to:
• perform an unthrottled intake air control by varying the opening and closing timing of the intake valve with a boost pressure within the intake manifold maintained substantially constant by adjusting a throttle position of the throttle valve;
• and
• provide a delay equivalent to a time constant due to a volume within the intake manifold downstream of the throttle valve to the varying opening and closing timing of the intake valve for the unthrottled intake air control and the adjusting throttle position of the throttle valve for the unthrottled intake air control.

A system for controlling intake air of an internal combustion engine, the engine having at least one combustion chamber, the system comprising:

• at least one intake valve provided for the combustion chamber;
• an electromagnetic driver operatively connected to each intake valve for opening said intake valve;
• an intake manifold with a throttle valve communicating with each intake valve;
• and
• sensors providing operation variables indicative of operator torque request command and engine speed;
• a control unit receiving said operation variables to determine a first operation parameter indicative of target intake air based on said operator torque request command and said engine speed,
• said control unit being operative to make a selection based on said first operation parameter indicative of target intake air between a first operation range for unthrottled intake air control and a second operation range for throttled intake air control, said first and second operation range being separated from each other by a threshold value of target intake air at each of varying values of engine speed, said threshold value increases as engine speed increases,
• said control unit being operative to vary, with valve opening timing held in the neighborhood of the top dead center, valve closure timing of said intake valve with said throttle valve held in the neighborhood of the wide open throttle position to perform unthrottled intake air control upon selection of said first operation range, and vary throttle valve position of said throttle valve with valve timing of said intake valve held to provide a valve opening duration in the neighborhood of a predetermined valve opening duration that is variable with varying engine speed to perform throttled intake air control upon selection of said second operation range,
• said control unit being operative to provide a response adjustment to said first operation parameter indicative of said target intake air to give a processed first operation parameter,
• said control unit being operative to determine a second operation parameter indicative of a target valve closure timing of said intake valve based on said processed first operation parameter,
• said control unit being operative to determine a third operation parameter indicative of a target throttle position of said throttle valve based on said processed first operation parameter, and
• said control unit being operative to control said electromagnetic driver to cause said intake valve to close at valve closure timing indicated by said second operation parameter and to control said throttle valve to assume throttle position indicated by said third operation parameter for unthrottled intake air control during said first operation range.