Aerostructure Actuator Slip Clutch for Over-Torque Protection
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Solution Overview
Problem
Aircraft aerostructures are prone to damage due to excessive torque and load during high-load events, which can exceed aircraft limit loads, causing self-damage to the actuator systems and structures.
Innovation Solution
The integration of a low-profile, low-inertia slip-clutch assembly within the drive shaft of the actuator system, which decouples the rotational speed between shaft portions if it exceeds a predefined limit, preventing excessive torque from being transmitted to the aerostructures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If a conventional actuator system is used to drive aerostructures, then the actuator can provide sufficient torque to move the aerostructure, but the drive shaft may apply excessive torque to the aerostructure during high load events, causing damage
Solution Approach 1:
A clutch assembly is introduced as an intermediary component between the drive shaft and the aerostructure. This clutch assembly includes friction surfaces that engage to transmit torque during normal operation but slip when excessive torque is detected, thereby protecting the aerostructure from damage while still allowing the actuator to provide sufficient driving force
Solution Approach 2:
The clutch assembly is designed with adjustable friction characteristics through spring pressure and friction surface selection. By changing the friction parameters, the system can be configured to transmit adequate torque for normal operation while automatically slipping at predetermined torque thresholds to prevent damage during high-load events
2Reliability
If a clutch assembly is added to prevent excessive torque, then protection against over-torque is improved, but the device complexity increases
Solution Approach 1:
The clutch assembly is integrated within the existing actuator system housing and share s common components such as the drive shaft connection and mounting structure. This merging approach allows the protective clutch mechanism to be added without proportionally increasing overall system complexity, as it utilizes the existing structural framework of the actuator
3Weight of moving object
If a compact clutch assembly is designed to minimize inertia, then the risk of self-damage during high-load events is reduced, but the manufacturing precision requirements increase
Solution Approach 1:
The clutch assembly is divided into discrete modular components including friction surfaces, springs, and retaining elements. This segmentation allows each component to be manufactured and assembled independently with controlled tolerances, reducing the cumulative precision requirements compared to a monolithic design while maintaining compact dimensions and low inertia
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
This solution effectively protects aerostructures by preventing over-torque and reducing the risk of damage, while offering a compact and lightweight design that minimizes inertia and potential for self-damage during flight operations.
Implementation Method 1
a first bearing installed on the post extension, a portion of the first bearing frictionally engaging with a portion of the post, a second bearing installed on the post
Implementation Method 2
a load setting nut configured to threadedly engage with the post extension and apply a compressive force to the first bearing, spacer, and the second bearing against the post
Data Source
AI summary
Aerostructure actuator systems include first and second shaft portions having respective first and second mandrels and a clutch assembly arranged within the first mandrel and connecting the shaft portions. The clutch assembly includes a post with a post extension fixedly connected to the second mandrel. A first bearing is installed on the post extension to frictionally engage with a portion of the post. A second bearing is installed on the post. A spacer is arranged between the bearings and is fixedly attach to the first mandrel. A load setting nut is configured to engage with the post extension and apply a compressive force to the bearings and spacer against the post. The compressive force defines a coupling limit between the shaft portions. The clutch assembly is configured to rotationally decouple the shaft portions from each other if a relative rotational speed between the shaft portions exceeds the coupling limit.