Redundant Linear Actuator with Non-Rotating Output

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Solution Overview

Problem

Existing aircraft landing gear actuators face reliability issues due to complexity in redundancy, space requirements, and challenges with non-rotating outputs, especially in failed states such as jammed or power-loss scenarios, which complicate the extension and locking mechanisms.

Innovation Solution

A redundant extension linear actuator with a single, non-rotating output is designed, featuring a primary and secondary linear module that can operate successively or simultaneously to extend the actuator, incorporating a positive extend lock mechanism for secure positioning and using anti-rotating power screw assemblies to ensure linear motion without rotating the output.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If multiple telescoping output parts are used to provide redundancy, then reliability is improved, but device complexity and space requirements increase

Engineering Contradiction:

ImprovereliabilityVSAvoiddevice complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The actuator is divided into two independent linear modules (first and second modules), each capable of independently extending the output. This segmentation provides redundancy while maintaining a relatively simple structure within each module, resolving the contradiction between reliability and device complexity.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Both linear modules share a common output and control system, merging their functions into a unified actuator assembly. This allows the system to achieve redundancy through multiple modules while avoiding the complexity of completely separate systems with multiple locking mechanisms.

Inventive Principle:

Principle #5Merging (Combining)

2Reliability

If back-to-back actuators with opposite extension directions are used, then redundancy is achieved, but space requirements and cabling complexity increase

Engineering Contradiction:

ImproveredundancyVSAvoidspace requirements

Core Design Contradiction:

ReliabilityVSArea of stationary object

Solution Approach 1:

Instead of using back-to-back actuators that extend in opposite directions, both linear modules are configured to extend in the same direction toward a common output. This inversion of the conventional back-to-back arrangement achieves redundancy while reducing space requirements and eliminating the need for special cabling to accommodate opposite movements.

Inventive Principle:

Principle #13The other way round (Inversion)

3Ease of operation

If a rotating output element is used, then actuator functionality is achieved, but sealing challenges and reliability issues arise

Engineering Contradiction:

Improveactuator functionalityVSAvoidsealing reliability

Core Design Contradiction:

Ease of operationVSReliability

Solution Approach 1:

The patent replaces the traditional rotating output element with a linear motion system using power screws and nuts. This substitution eliminates the rotating output that causes sealing challenges, while still achieving the required actuator functionality through linear extension and retraction of the common output.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

4Reliability

If separate locking mechanisms are used for each output part, then reliability is improved, but device complexity and position indication difficulty increase

Engineering Contradiction:

ImprovereliabilityVSAvoidlocking mechanism complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

Both linear modules share a common output and can be controlled to extend or retract together, effectively merging their locking functions. This approach provides redundancy while avoiding the complexity of separate locking mechanisms for each module, as the shared output and coordinated control simplify the overall locking and position indication system.

Inventive Principle:

Principle #5Merging (Combining)

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 design enhances reliability and simplifies the locking mechanism, reducing space requirements and enabling operation in failed states by providing a fail-safe, redundant system that maintains aircraft landing gear in a down and locked condition.

Implementation Method 1

using anti-rotating power screw assemblies to ensure linear motion without rotating the output

Methodology Applied

Scientific EffectScrew mechanism: Screw

Data Source

PatentUS9933058B1Redundant extension linear actuator and methods of use

Publication Date: 2018.04.03 WOODWARD INC

AI summary

An actuator having an output slidable between extended and retracted positions is provided. The actuator includes a primary module having a power drive, power screw rotatable by the power drive, and a nut operable to translate rotation of the power screw to linear motion of the nut across the power screw. The actuator includes a secondary module having a power drive, a shaft rotatable by the power drive, a power screw, and a nut. The power screw is slidably coupled to and rotatable by the shaft, and coupled to the output. The nut is coupled to the power screw and is operable to slide linearly across the shaft by rotating through the nut. Both the primary nut and secondary power screw are operable to move the output to the extended position or the retracted position depending on the rotational direction of the primary power screw and secondary power screw.