Control logic for a propeller system
A propeller control system includes a propeller control logic subsystem in conjunction with an engine control logic subsystem to provide an optimized transition from forward to reverse speed governing under all operating conditions. By creating a Propeller control Mode (PCM) map relative the blade angle and Power Lever Angle (PLA), the minimum blade angle allowed for forward speed governing and the maximum blade angle allowed for reverse speed governing is determined. By combining the actual propeller blade angle, the min and max angles for speed governing, and the PLA signal, the state of the propeller speed governor is determined.
1. A method of transitioning between forward and reverse governing of a propeller system comprising the steps of:
determining a power level angle;
determining a propeller blade angle; and
looking up a Propeller Control Mode cell from a Propeller Control Mode map in response to the power level angle and the propeller blade angle;
transitioning from a forward governing range to a reverse governing range on the propeller control mode map in response to the propeller blade angle reaching a minimum forward blade angle or transitioning from the reverse governing range to the forward governing range on the propeller control mode map in response to the propeller blade angle reaching a maximum reverse blade angle;
passing through a speed governors disabled mode cell on the Propeller Control Mode map while transitioning during which propeller speed is not controlled;
resuming propeller speed governing in either the forward speed governing range or the reverse speed governing range on the Propeller Control Mode map after passing through the speed governors disabled mode cell;
looking up a propeller min power request from the propeller control mode map; and
communicating the propeller min power request to an engine control logic system.
2. The method as recited in claim 1 , further comprising the steps of:
looking up a reference propeller speed on the Propeller Control Mode map;
communicating the reference propeller speed to the engine control logic subsystem.
3. A method of transitioning between forward and reverse governing of a propeller system comprising the steps of:
determining a minimum blade angle permitted for forward speed governing from a Propeller Control Mode map which relates a Power Lever Angle to a propeller blade angle;
determining a maximum blade angle allowed for reverse speed governing from the Propeller Control Mode map which relates the Power Lever Angle to the propeller blade angle;
determining when the propeller reaches the minimum blade angle permitted for forward speed governing or the maximum blade angle permitted for reverse speed governing;
transitioning from the forward governing range to the reverse governing range on the propeller control mode map in response to the propeller blade angle reaching the minimum forward blade angle or transitioning from the reverse governing range to the forward governing range on the propeller control mode map in response to the propeller blade angle reaching the maximum reverse blade angle;
passing through a speed governors disabled mode cell on the Propeller Control Mode map while transitioning during which propeller speed is not controlled;
resuming propeller speed governing in either the forward speed governing range or the reverse speed governing range on the Propeller Control Mode map after passing through the speed governors disabled mode cell; and
determining a propeller minimum power request by looking up a Propeller Control Mode cell from the Propeller Control Mode map.
4. A method as recited in claim 3 , further comprising the step of:
determining a reference propeller speed by looking up a Propeller Control Mode cell from the Propeller Control Mode map.
5. A method as recited in claim 3 , further comprising the step of:
determining a governor state by looking up a Propeller Control Mode cell from the Propeller Control Mode map.