Actuator Nut Assembly With Polymer Insert for Wear and Load Balance

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Solution Overview

Problem

Conventional metal-to-metal actuator configurations in aircraft engines experience excessive wear and require additional features like lubrication, while engineered plastic nuts against metallic screws have a lower wear rate but still face performance issues.

Innovation Solution

A nut assembly comprising an outer metal nut portion and an inner polymer nut portion with microthreads and anti-rotation pins, allowing for differential material usage and improved load distribution, enhancing wear performance and reducing weight.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If metal-to-metal actuator configurations are used, then strength and load-bearing capacity are improved, but wear increases and lubrication is required

Engineering Contradiction:

Improveload-bearing capacityVSAvoidwear resistance

Core Design Contradiction:

StrengthVSReliability

Solution Approach 1:

The nut assembly combines metal outer portion with polymer inner portion containing microthreads, creating a composite structure that leverages the strength of metal and the low-wear properties of polymer materials to simultaneously achieve high load-bearing capacity and wear resistance

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The microthreaded polymer inner portion is nested within the metal outer nut portion, allowing the polymer component to bear operational loads and resist wear while the metal outer portion provides structural strength and load distribution

Inventive Principle:

Principle #7Nested doll (Nesting)

2Reliability

If engineered plastic nuts are used against metallic screws, then wear rate is reduced, but load-bearing capacity decreases

Engineering Contradiction:

Improvewear resistanceVSAvoidload-bearing capacity

Core Design Contradiction:

ReliabilityVSStrength

Solution Approach 1:

The dual-material construction combines polymer inner portion for low wear with metal outer portion for high strength, enabling the assembly to achieve both wear resistance and adequate load-bearing capacity that neither material could provide alone

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The nut is divided into functional segments: the polymer inner portion handles thread engagement and wear resistance, while the metal outer portion handles load distribution and structural requirements, with each segment optimized for its specific function

Inventive Principle:

Principle #1Segmentation

3Ease of manufacture

If uniform material construction is used, then manufacturing is simplified, but performance and wear characteristics are compromised

Engineering Contradiction:

Improvemanufacturing simplicityVSAvoidwear performance

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The assembly uses different materials (metal and polymer) in specific configurations to optimize performance characteristics, demonstrating that enhanced wear performance justifies the increased manufacturing complexity of multi-material construction

Inventive Principle:

Principle #40Composite materials

Data Source

PatentEP4491907A1Nut for actuator system and actuator system comprising the same

Publication Date: 2025.01.15 HAMILTON SUNDSTRAND CORP

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AI summary

A nut for use in an actuator assembly having a rotatable screw includes an outer nut portion (62) and an inner nut portion (60) removably coupled to the outer nut portion (62). The inner nut portion (60) is rotatably couplable to the rotatable screw. At least one anti-rotation pin (90) is positionable between the outer nut portion (62) and the inner nut portion (60) to restrict rotation of the inner nut portion (60) relative to the outer nut portion (62).