Clutch-Brake Actuation Architecture for Aircraft Jam Loads
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Solution Overview
Problem
Aircraft actuation systems face issues with jamming, leading to excessive loads on the structure, resulting in weight penalties due to the need for oversized components to withstand these loads, which is undesirable.
Innovation Solution
Incorporating a clutch in the transmission line between the power drive unit and actuators, coupled with sensors to detect abnormal load conditions and a brake to rapidly disconnect power and prevent uncontrolled movement, thereby mitigating excessive loads without the need for mechanical torque limiters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the structure is sized to resist excessive loading from jammed components, then system strength is improved, but aircraft weight increases
Solution Approach 1:
The clutch is configured to proactively disconnect the power drive unit from actuators when abnormal load conditions are detected, preventing excessive loads from developing in the first place. This preliminary protective action eliminates the need to design structures to withstand worst-case jamming scenarios, thereby reducing weight while maintaining strength under normal operating conditions.
Solution Approach 2:
The clutch acts as an intermediary device between the power drive unit and actuators, selectively engaging or disengaging the power transmission based on load conditions. This mediator protects the system from excessive loads without requiring the entire structure to be oversized, resolving the contradiction between strength and weight.
2Reliability
If mechanical torque limiters are used to prevent excessive loads, then system protection is improved, but device complexity increases
Solution Approach 1:
The system replaces mechanical torque limiters with an electronically controlled clutch system that uses sensors to detect abnormal loads and a control unit to disengage the clutch. This substitution of mechanical protection devices with an electronic control system reduces mechanical complexity while maintaining or improving system protection capabilities.
Solution Approach 2:
The system incorporates sensors that continuously monitor load conditions and provide feedback to the clutch control unit. When abnormal loads are detected, the control unit disengages the clutch to protect the system. This feedback-based protection mechanism is simpler and more reliable than mechanical torque limiters while providing equivalent or superior system protection.
Data Source
AI summary
An actuation system comprises a plurality of actuators, a common power drive unit for driving the actuators and a transmission line transmitting drive from the common drive unit to the plurality of actuators. A clutch is arranged in the transmission line between the power drive unit and the plurality of actuators for selectively disconnecting the power drive unit from the plurality of actuators. At least one sensor is provided for sensing an abnormal load condition in the actuation system. The at least one sensor is operatively coupled to a clutch control which is configured such that when the at least one sensor senses an abnormal load condition, the clutch control is operative to disengage the clutch so as to disconnect the power drive unit from the plurality of actuators. A brake is operative to brake the actuators upon disengagement of the clutch.