Multimode Clutch Assembly for Rotorcraft Supplemental Torque Transfer
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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 bidirectional torque transfer between the main drive system and a secondary engine, 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: it provides accessory power during preflight operations and can also provide 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, transforming it from a single-function accessory power source to a multi-function power source that can directly drive the main rotor.
2Power
If bidirectional torque transfer is enabled, then the secondary engine can provide power to the main rotor, but the overrunning mode capability is lost
Solution Approach 1:
The clutch assembly incorporates a bypass assembly that can dynamically shift between two configurations: engaged and disengaged. In the disengaged position, the freewheeling unit operates in overrunning mode allowing unidirectional torque transfer. In the engaged position, the bypass assembly couples the input and output races, enabling bidirectional torque transfer. This dynamic reconfiguration allows the system to adapt its torque transfer characteristics based on operational requirements.
3Reliability
If pressurized lubricating oil is used for engagement force, then reliable engagement is maintained, but system complexity increases
Solution Approach 1:
The actuator assembly utilizes pressurized lubricating oil from the engine's lubrication system to generate engagement force. The oil pressure acts on a piston within the actuator, creating the force necessary to maintain the bypass assembly in the engaged position. This hydraulic approach leverages the existing lubrication system's pressure to provide reliable engagement without requiring a separate, complex actuation system.
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 and accessories, enhancing the rotorcraft's efficiency and safety by allowing the main engine to be downsized, and providing emergency power in case of main engine failure.
Implementation Method 1
an actuator assembly having a default configuration in which a pressurized lubricating oil 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.