Multimode Rotorcraft Clutch Assembly for Bidirectional 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 utilizing pressurized lubricating oil to switch between unidirectional and bidirectional torque transfer modes, allowing the secondary engine to support 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 can provide accessory power during preflight operations and 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, allowing it to function as both an accessory driver and a supplemental propulsion source.
Solution Approach 2:
The clutch assembly dynamically switches between unidirectional and bidirectional torque transfer modes based on operational requirements. The bypass assembly can be positioned to enable or disable the overrunning mode of the freewheeling unit, allowing the system to adapt its power transfer characteristics in real-time to match flight conditions.
2Ease of operation
If a freewheeling unit with overrunning mode is used, then unidirectional torque transfer is enabled, but bidirectional torque transfer cannot be achieved
Solution Approach 1:
The clutch assembly dynamically switches between unidirectional and bidirectional torque transfer modes based on operational requirements. The bypass assembly can be positioned to enable or disable the overrunning mode of the freewheeling unit, allowing the system to adapt its power transfer characteristics in real-time to match flight conditions.
Solution Approach 2:
The bypass assembly acts as an intermediary mechanism that can selectively connect or disconnect the input and output races of the freewheeling unit. By positioning the bypass assembly in different locations, it mediates between the freewheeling unit's natural unidirectional operation and the requirement for bidirectional torque transfer, enabling flexible operational modes.
3Adaptability or versatility
If the bypass assembly is always in the engaged position, then bidirectional torque transfer is enabled, but the overrunning mode cannot be utilized
Solution Approach 1:
The clutch assembly dynamically switches between unidirectional and bidirectional torque transfer modes based on operational requirements. The bypass assembly can be positioned to enable or disable the overrunning mode of the freewheeling unit, allowing the system to adapt its power transfer characteristics in real-time to match flight conditions.
4Extent of automation
If a lock assembly with engagement signal is used, then controlled actuation is enabled, but actuation cannot occur when engagement signal is absent
Solution Approach 1:
The lock assembly uses an engagement signal (such as an oil pressure signal) to control the actuation of the bypass assembly. The system continuously monitors the engagement signal and only allows actuation when the signal is present, ensuring that the bypass assembly is only repositioned under controlled conditions when the engine is properly engaged and ready for operation.
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 provide power to the main rotor and accessories, enhancing the rotorcraft's efficiency and safety by allowing bidirectional torque transfer, thereby supporting high power demand operations and ensuring continued operation in case of main engine failure.
Implementation Method 1
An actuator assembly is configured to utilize a pressurized lubricating oil to generate an engagement signal that biases the bypass assembly toward the engaged position and a disengagement signal that biases the bypass assembly toward the disengaged 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 and an overrunning mode in which torque applied to the output race is not transferred to the input race
Data Source
AI summary
A failsafe multimode clutch assembly positioned in a powertrain of a rotorcraft. The clutch assembly includes a freewheeling having 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 uses pressurized lubricating oil to shift the bypass assembly between the engaged position and a disengaged position. A lock assembly enables and disables actuation of the bypass assembly. In the disengaged position, the overrunning mode of the freewheeling unit enables a unidirectional torque transfer mode of the clutch assembly. In the engaged position, the overrunning mode of the freewheeling unit is disabled such that the clutch assembly is configured for bidirectional torque transfer.