Multimode Clutch Assembly for Bidirectional Rotorcraft Power Transfer
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Solution Overview
Problem
Conventional rotorcraft systems lack the capability for an auxiliary power unit to provide supplemental power to the main rotor during high power demand flight operations, limiting their versatility and efficiency.
Innovation Solution
A multimode clutch assembly with a freewheeling unit, bypass assembly, and actuator assembly, along with engagement status sensors, enables bidirectional torque transfer between the main and secondary engines, allowing the secondary engine to provide power to the main rotor and accessories, enhancing power efficiency and safety.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a conventional auxiliary power unit is used, then preflight accessory power is provided, but supplemental power to the main rotor during high power demand flight operations is not available
Solution Approach 1:
The clutch assembly enables the auxiliary power unit to dynamically switch between two operational modes: preflight mode (overrunning mode) where the auxiliary power unit only drives accessories, and flight mode (engaged mode) where it provides supplemental power to the main rotor. The bypass assembly acts as a dynamic coupling mechanism that can engage or disengage based on flight conditions, allowing the system to adapt its power delivery capability.
Solution Approach 2:
The auxiliary power unit is designed with multi-functionality through the clutch assembly, enabling it to serve dual purposes: (1) driving accessories during preflight operations in overrunning mode, and (2) providing supplemental power to the main rotor during high power demand flight operations in engaged mode. This universal design eliminates the need for separate dedicated auxiliary and supplemental power units.
2Adaptability or versatility
If a freewheeling unit is used to enable overrunning mode, then unidirectional torque transfer is achieved, but bidirectional torque transfer capability is lost
Solution Approach 1:
The bypass assembly serves as an intermediary mechanical element that can either engage to couple the input and output races (enabling bidirectional torque transfer) or disengage to allow the freewheeling unit to operate in overrunning mode (unidirectional torque transfer). This intermediary component mediates between the conflicting requirements of unidirectional and bidirectional torque transfer, allowing the system to switch between operational modes without direct complex control mechanisms.
3Reliability
If engagement status sensors are added, then engagement status determination is enabled, but device complexity increases
Solution Approach 1:
Engagement status sensors are integrated into the clutch assembly to provide real-time feedback on the engagement state of the bypass assembly. This feedback mechanism allows the flight control system to monitor and respond to the clutch's operational mode, enhancing reliability by ensuring the auxiliary power unit operates as intended. The sensors provide critical information for safety and performance optimization without requiring complex manual monitoring systems.
Data Source
AI summary
A multimode clutch assembly is positioned in a powertrain of a rotorcraft. The clutch assembly includes a freewheeling unit 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 shifts the bypass assembly between engaged and disengaged positions. An engagement status sensor is configured to determine the engagement status of the bypass assembly. 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.