Rotorcraft Supplemental Engine Control for Stable Rotor Speed
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Solution Overview
Problem
Conventional rotorcraft systems employing engine control units for rotor speed control face limitations in effectively managing power distribution between main and supplemental engines, particularly in varying load conditions.
Innovation Solution
A drive system comprising a main rotor coupled to a main rotor gearbox and a supplemental engine, where the main engine is controlled based on rotor speed variations using a power compensation command, and the supplemental engine provides additional power in response to a supplemental power demand, with a control system managing the total power demand to maintain rotor speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the supplemental engine is controlled to regulate rotor speed, then rotor speed control capability is improved, but the complexity of the control system increases
Solution Approach 1:
A clutch assembly is introduced as an intermediary component between the supplemental engine and the main rotor drive system. The clutch selectively engages or disengages the supplemental engine based on operational conditions, allowing the supplemental engine to contribute to rotor speed control only when needed, thereby improving control capability without requiring continuous complex coordination
Solution Approach 2:
The control system dynamically adjusts the engagement state of the clutch assembly based on real-time operational parameters such as rotor speed deviations and power demand. This dynamic control allows the supplemental engine to be activated only when rotor speed control is needed, optimizing performance while minimizing control system complexity during normal operation
2Power
If the supplemental engine provides additive power, then available power is improved, but the complexity of the powertrain system increases
Solution Approach 1:
The powertrain is segmented into a main drive system and a supplemental power system with a clutch assembly. The supplemental engine operates as a separate, independently controllable unit that can be engaged to provide additive power when needed, such as during high power demand or main engine failure, without requiring integration complexity into the main engine's continuous operation
Solution Approach 2:
The clutch assembly serves multiple functions: it enables the supplemental engine to provide additive power during high demand, allows the supplemental engine to assist in rotor speed control, and can be disengaged to isolate the supplemental engine from the main drive system. This multi-functionality reduces the need for separate control mechanisms for each function
3Reliability
If the main engine is isolated from the supplemental engine, then reliability during main engine failure is improved, but the ability to share load between engines is reduced
Solution Approach 1:
The clutch assembly acts as an isolating intermediary that can disconnect the supplemental engine from the main drive system. During main engine failure, the clutch can be engaged to allow the supplemental engine to provide necessary power without being mechanically coupled to the failed main engine, preventing failure propagation while maintaining operational capability
Solution Approach 2:
The clutch assembly dynamically transitions between engaged and disengaged states based on operational conditions. During normal operation, the clutch may be disengaged to allow load sharing and power summation. During main engine failure, the clutch is engaged to isolate the supplemental engine from the failed main engine, ensuring reliability while maintaining productivity through supplemental power
Data Source
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AI summary
A rotorcraft (10) has a drive system including a main rotor (12) coupled to a main rotor gearbox (34) to rotate the main rotor (12) at a rotor speed, a main engine (32) coupled to the drive system to provide a first power, a supplemental engine (40) coupled, when a first clutch is engaged, to the drive system to provide a second power additive to the first power, and a control system operable to control the main engine (32) and the supplemental engine (40) to provide a total power demand, where the main engine (32) is controlled based on variations in rotor speed and a power compensation command to produce the first power, and the supplemental engine (40) is controlled to produce the second power in response to a supplemental power demand.