Failsafe Multimode Clutch Assembly for Rotorcraft Power Sharing
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Solution Overview
Problem
Conventional rotorcraft systems lack the capability for their auxiliary power units to provide supplemental power to the main rotor during high power demand flight operations, limiting their versatility and efficiency.
Innovation Solution
A failsafe multimode clutch assembly that includes a freewheeling unit, a bypass assembly, and an actuator assembly, allowing for unidirectional or bidirectional torque transfer between the main and secondary engines, enabling the secondary engine to provide power to the main rotor during high power demand conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a conventional auxiliary power unit is used, then accessory power during preflight operations is provided, but supplemental power to the main rotor during high power demand flight operations cannot be provided
Solution Approach 1:
The auxiliary power unit is designed to perform multiple functions: providing accessory power during preflight operations and providing supplemental power to the main rotor during high power demand flight operations. The clutch assembly enables the auxiliary power unit to couple with the main rotor drive system, allowing it to serve as both an accessory driver and a supplemental propulsion source.
Solution Approach 2:
The clutch assembly dynamically switches between engaging and disengaging the auxiliary power unit with the main rotor drive system based on operational requirements. The bypass assembly allows selective coupling/decoupling of the auxiliary power unit output to the main rotor, enabling the system to adapt its power transfer characteristics during different flight phases.
2Adaptability or versatility
If bidirectional torque transfer is enabled, then the secondary engine can power the main rotor, but the risk of unintended engagement increases
Solution Approach 1:
The mechanical biasing element is pre-configured to maintain the bypass assembly in the engaged position, ensuring that bidirectional torque transfer is the default safe state. The disengagement element must be actively activated to override this bias and decouple the auxiliary power unit, preventing unintended engagement through passive failure modes.
Solution Approach 2:
The bypass assembly acts as an intermediary mechanism between the auxiliary power unit and the main rotor drive system. It provides a controlled interface that enables bidirectional torque transfer when needed while maintaining safety through the mechanical biasing system that prevents accidental coupling.
3Weight of moving object
If the main engine is downsized, then weight and complexity are reduced, but the available power for high power demand operations decreases
Solution Approach 1:
The system merges the power output of the main engine with the auxiliary power unit through the clutch assembly. During high power demand operations, both engines contribute torque to the main rotor, combining their capabilities to achieve the required power level while allowing each engine to be sized more efficiently than a single large engine.
Solution Approach 2:
The auxiliary power unit provides partial power supplementation during high power demand operations rather than requiring the main engine to provide excessive power capacity for all scenarios. This allows the main engine to be downsized to match typical operational requirements while the auxiliary unit fills the power gap during peak demand.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables the secondary engine to supply power to the main rotor during high power demand operations, enhancing the rotorcraft's efficiency and safety by allowing the main engine to be downsized, and providing emergency power in case of failure.
Implementation Method 1
a mechanical biasing element provides an engagement force that maintains the bypass assembly in the engaged position
Implementation Method 2
The freewheeling unit has a driving mode in which torque applied to the input race is transferred to the output race
Data Source
AI summary
A failsafe multimode clutch assembly is positioned in a powertrain of a rotorcraft. The clutch assembly includes a freewheeling unit having input and output races. The freewheeling unit has a driving mode in which torque applied to the input race is transferred to the output race and an overrunning mode in which torque applied to the output race is not transferred to the input race. A bypass assembly has an engaged position that couples the input and output races of the freewheeling unit. An actuator assembly must be energized to shift the bypass assembly from the engaged position to a disengaged position. In the disengaged position, the overrunning mode of the freewheeling unit is enabled such that the clutch assembly is configured for unidirectional torque transfer. In the engaged position, the overrunning mode of the freewheeling unit is disabled such that the clutch assembly is configured for bidirectional torque transfer.