Skewed-Roller Torque Limiter for Passive Bidirectional Threshold Control
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Solution Overview
Problem
Existing torque limiters for aircraft flight control surfaces require electronic control systems for asymmetric torque limiting, which can be unreliable in case of electronic failure, and there is a need for a compact and lightweight passive mechanical solution.
Innovation Solution
An asymmetric torque limiter comprising a first annular friction disk, a second annular friction disk, a skewed roller disk, a first resilient member, and a second resilient member, which allows for different torque thresholds in clockwise and anticlockwise directions without electronic control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If electronic control systems are used for asymmetric torque limiting, then torque control precision is improved, but system reliability deteriorates due to electronic failure risk
Solution Approach 1:
The patent replaces electronic control systems with a purely mechanical asymmetric torque limiting mechanism. The mechanism uses a friction disk, skewed roller, and resilient members to automatically limit torque in different directions without electronic sensors or actuators, eliminating electronic failure risks while maintaining torque control precision through mechanical design parameters such as skew angle and friction coefficients.
2Device complexity
If passive mechanical torque limiter is designed to be compact and lightweight, then device complexity is reduced, but torque limiting performance may deteriorate
Solution Approach 1:
The torque limiter is segmented into distinct functional components: a friction disk for torque transmission, skewed rollers for asymmetric force conversion, and resilient members for biasing. This segmentation allows each component to be optimized independently for both compactness and performance, reducing overall device complexity while maintaining reliable torque limiting through precise geometric relationships between segments.
Solution Approach 2:
The patent employs asymmetric geometry in the roller skew angle and friction interface design to achieve different torque limits in clockwise and anticlockwise directions. This asymmetric configuration allows the compact mechanical structure to inherently provide direction-dependent torque limiting performance without complex control systems, maintaining both compactness and reliability.
3Reliability
If asymmetric torque limiting is achieved without electronic systems, then system reliability is improved, but device complexity increases due to mechanical components
Solution Approach 1:
The mechanical torque limiter is designed as a self-service system where the skewed rollers automatically convert rotational torque into asymmetric axial forces on the friction disk through their geometric skew. The resilient members self-bias the friction disk against the skewed rollers, creating automatic torque limiting in both directions without external control systems, thereby improving reliability while keeping the mechanical structure relatively simple.
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
The solution provides a passive, compact, and lightweight torque limiter that effectively limits torque asymmetrically, ensuring the safety of aircraft flight control surfaces by preventing mechanical overload without relying on electronic systems.
Implementation Method 1
The first resilient member is attached to the first annular friction disk and is configured to bias the first annular friction disk toward an input shaft
Implementation Method 2
The second resilient member is configured to bias the skewed roller disk toward the second annular friction disk
Implementation Method 3
The skewed roller disk is in contact with the second annular friction disk. The skewed roller disk includes a plurality of skewed rollers mounted in an annular retainer. The plurality of skewed rollers are each rotatable about a respective roller axis, each roller axis being skewed with respect to a radial direction passing through the skewed roller from the axis of rotation
Data Source
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AI summary
There is provided an asymmetric torque limiter (30) having an axis of rotation (A) including a first annular friction disk (42), a second annular friction disk (46) a skewed roller disk (48) a first resilient member (44) and a second resilient member (60). The second annular friction disk (46) is concentrically arranged with the first annular friction disk (42). The skewed roller disk (48) is in contact with the second annular friction disk (46). The skewed roller disk (48) includes a plurality of skewed rollers (52) mounted in an annular retainer (50). The plurality of skewed rollers (52) are each rotatable about a respective roller axis, each roller axis being skewed with respect to a radial direction passing through the skewed roller (52) from the axis of rotation (A). The first resilient member (44) is attached to the first annular friction disk (42) and is configured to bias the first annular friction disk (42) toward an input shaft (32). The second resilient member (60) is configured to bias the skewed roller disk (48) toward the second annular friction disk (46).