Compressible Ramp Roller Torque Limiter for Aircraft

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Solution Overview

Problem

Conventional torque limiters in aircraft systems suffer from variability and inconsistency due to friction effects, leading to a wide torque bandwidth that necessitates over-engineering and increased weight, as the friction at multiple interfaces is unpredictable and contributes significantly to the torque limiter's range of operation.

Innovation Solution

A reduced friction torque limiter design featuring a compressible ramp roller element with circumferential slots and an integral output gear, eliminating the need for Belleville springs and sliding interfaces, thereby reducing friction and torque bandwidth, allowing for lighter and smaller component design.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional torque limiters with multiple friction interfaces are used, then the torque limiter can provide a range of torque limits, but the torque bandwidth becomes wide and the design requires over-engineering with heavier materials

Engineering Contradiction:

Improvetorque limiter operationVSAvoidaircraft component weight

Core Design Contradiction:

ReliabilityVSWeight of moving object

Solution Approach 1:

The patent removes friction interfaces from the torque limiter mechanism by replacing sliding contacts with rolling element bearings. This extraction of friction eliminates the need for multiple friction interfaces while maintaining torque limiting functionality, thereby reducing the torque bandwidth and allowing lighter component design

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent substitutes a rolling element bearing mechanism for the conventional sliding friction interface. This mechanical substitution replaces the friction-based torque limitation with a rolling contact system that minimizes friction, reducing torque bandwidth variability

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Adaptability or versatility

If conventional torque limiters with multiple friction interfaces are used, then the torque limiter can operate with spring mechanisms, but the friction effects cause variability in torque limit settings

Engineering Contradiction:

Improvetorque limiter setting rangeVSAvoidtorque limit value consistency

Core Design Contradiction:

Adaptability or versatilityVSManufacturing precision

Solution Approach 1:

The patent extracts and eliminates the friction interfaces that cause variability in torque limit settings. By removing sliding contacts and replacing them with rolling element bearings, the design achieves consistent and repeatable torque limiting without the variability introduced by friction at multiple interfaces

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent changes the fundamental parameter of contact type from sliding to rolling. This parameter change transforms the friction characteristics from high and variable (sliding) to low and consistent (rolling), thereby improving manufacturing precision and torque limit value consistency

Inventive Principle:

Principle #35Parameter changes

3Force

If conventional torque limiters with sliding interfaces are used, then the mechanism can provide torque limitation, but the friction at various points increases the torque bandwidth

Engineering Contradiction:

Improvetorque limitation capabilityVSAvoidtorque bandwidth range

Core Design Contradiction:

ForceVSDevice complexity

Solution Approach 1:

The patent substitutes rolling element bearings for sliding friction interfaces. This mechanical substitution maintains the torque limitation capability while eliminating the friction that contributes to torque bandwidth, thereby simplifying the device by reducing the range of torques that must be accommodated

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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 significantly reduces the torque limiter's bandwidth, enabling lighter and more efficient aircraft components, improved design optimization, and increased Mean Time Between Failures (MTBF) by minimizing friction-related variations and eliminating multiple spring and friction plate systems.

Implementation Method 1

an overtorque condition causes axial compression of said output ramp roller element

Methodology Applied

Scientific EffectElastic deformation: Elasticity

Data Source

PatentUS9945460B2Torque limiter

Publication Date: 2018.04.17 GOODRICH ACTUATION SYST

AI summary

A torque limiter comprising: a ramp roller, said ramp roller comprising: an input ramp roller element arranged to be driven by an input torque and having a first ramp surface; an output ramp roller element arranged to drive an output torque shaft and having a second ramp surface; ramp roller balls disposed between the first ramp surface and the second ramp surface; wherein said output ramp roller element is axially and resiliently compressible and wherein an overtorque condition causes axial compression of said output ramp roller element. This arrangement removes all axially sliding friction surfaces from the torque limiter so that the torque bandwidth is reduced, allowing manufacturers to design structures more optimally.