Composite Actuator Nut Assembly for Wear-Resistant Load Transfer

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Solution Overview

Problem

Conventional metal-to-metal actuator configurations in aircraft engines, such as those used for cowl doors, experience excessive wear and require additional features like lubrication, while engineered plastic nuts against metallic screws have a lower wear rate but still face challenges.

Innovation Solution

A nut assembly comprising an outer metal nut portion and an inner polymer nut portion with anti-rotation pins and microthreads, allowing for differential thread pitches and material combinations to enhance wear resistance and load distribution.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If metal-to-metal actuator configurations are used, then structural strength and load-bearing capacity are improved, but excessive wear occurs and additional lubrication features are required

Engineering Contradiction:

Improvestructural strengthVSAvoidwear resistance

Core Design Contradiction:

StrengthVSReliability

Solution Approach 1:

The nut assembly combines metal outer portions with a polymer inner portion to create a composite structure. The metal provides structural strength and load-bearing capacity, while the polymer provides self-lubrication properties and wear resistance, eliminating the need for additional lubrication features.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

Different portions of the nut assembly have different material properties optimized for their specific functions. The outer metal portions handle structural loads, while the inner polymer portion handles friction and wear, allowing each region to have the quality needed for its specific role.

Inventive Principle:

Principle #3Local quality

2Reliability

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

Engineering Contradiction:

Improvewear resistanceVSAvoidload-bearing capacity

Core Design Contradiction:

ReliabilityVSStrength

Solution Approach 1:

The nut assembly uses a composite structure with metal outer portions for load-bearing and a polymer inner portion for wear resistance. This combination allows the structure to handle high loads while maintaining low wear rates.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The nut is divided into multiple portions with different materials - metal outer portions and polymer inner portion - each optimized for specific functions. The segmented structure allows simultaneous achievement of strength and wear resistance.

Inventive Principle:

Principle #1Segmentation

3Ease of manufacture

If a single-material nut assembly is used, then manufacturing simplicity is maintained, but wear performance and load distribution are insufficient

Engineering Contradiction:

Improvemanufacturing simplicityVSAvoidwear performance

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The nut assembly uses composite materials (metal and polymer) to achieve superior wear performance and load distribution. The different materials are joined through threading and anti-rotation mechanisms, maintaining manufacturability while improving reliability.

Inventive Principle:

Principle #40Composite materials

Data Source

PatentUS20250020156A1Nut design for actuator system

Publication Date: 2025.01.16 HAMILTON SUNDSTRAND CORP

AI summary

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