Threaded Spring Preload Locking for Precise RAT Deployment

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Solution Overview

Problem

Current deployment actuators for ram air turbines (RATs) lack precise control over deployment time due to limitations in adjusting spring preload, which can lead to component damage during deployment in strong cross winds and turbulence.

Innovation Solution

A spring compression device with a spring sleeve and adjustment member that includes a blocking component to set and maintain the operating length, allowing for adjustable preload through a threaded connection and grip features for tool engagement, enabling precise adjustment of spring compression.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If shims are provided to adjust auxiliary spring preload, then deployment time control is improved, but device complexity increases

Engineering Contradiction:
Improvedeployment time controlVSAvoiddevice complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The adjustment mechanism is segmented into modular components: a blocking component, a blocking component holder, and alignment features (recesses and protrusions). This segmentation allows for precise incremental adjustments to spring preload while maintaining a relatively simple overall structure. Each component performs a specific function that contributes to the cumulative precision of deployment time control.

Inventive Principle:
Principle #1Segmentation

2Reliability

If spring preload is adjusted to compensate for machining tolerances, then reliability is improved, but manufacturing precision requirements increase

Engineering Contradiction:
ImprovereliabilityVSAvoidmanufacturing precision
Core Design Contradiction:
ReliabilityVSManufacturing precision

Solution Approach 1:

The blocking component is pre-configured with specific alignment features (recesses and protrusions) that guide its insertion and positioning. This preliminary configuration ensures that even with normal machining tolerances, the spring preload will be within the desired range. The alignment features perform the preliminary action of positioning the blocking component correctly, eliminating the need for high-precision machining while ensuring reliable deployment.

Inventive Principle:
Principle #10Preliminary action

3Measurement precision

If the number of auxiliary springs is increased to control deployment, then deployment control is improved, but device complexity increases

Engineering Contradiction:
Improvedeployment controlVSAvoiddevice complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

Instead of increasing the number of auxiliary springs, the invention changes the parameter of spring preload by adjusting the initial compression of the auxiliary spring. The blocking component allows precise adjustment of this preload parameter, enabling better deployment control with the same number of springs. This parameter change approach achieves improved control without increasing device complexity.

Inventive Principle:
Principle #35Parameter changes

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 precise control over spring preload, ensuring safe and controlled deployment of RATs by allowing adjustment of the spring compression device to match operational requirements, reducing the need for high-precision springs and enhancing reliability.

Implementation Method 1

a spring compression device, comprising: a spring sleeve configured to receive a spring; a spring adjustment member provided on and engaged with the spring sleeve and configured to abut a spring mounted on the spring sleeve, wherein: the spring sleeve and spring adjustment member define an operating length of the spring compression device

Methodology Applied
Scientific EffectElastic deformation: Elasticity

Implementation Method 2

at least one blocking component for blocking movement between the spring sleeve and the spring adjustment member (e.g., once the operating length has been set)

Methodology Applied
Scientific EffectMechanical blocking: Mechanical Fastener

Data Source

PatentEP3263944B1Spring compression device
Publication Date: 2022.06.22 HAMILTON SUNDSTRAND CORP
  • EP3263944B1 patent drawingFigure 1A~1B
  • EP3263944B1 patent drawingFigure 2A~2B
  • EP3263944B1 patent drawingFigure 3A~3B

AI summary

A spring compression device (100) comprises a spring sleeve (110) configured to receive a spring (210); a spring adjustment member (130) provided on and engaged with the spring sleeve and configured to abut a spring (210) mounted on the spring sleeve, wherein the spring sleeve and spring adjustment member define an operating length (L) of the spring compression device, and the spring adjustment member is configured to be moved relative to the spring sleeve to adjust the operating length of the spring compression device; and at least one blocking component (140) for blocking movement between the spring sleeve and the spring adjustment member. The spring sleeve and spring adjustment member may be engaged with a threaded connection (120). An exterior surface of the spring sleeve and an interior surface (135) of the spring adjustment member may each have at least one recess (116, 136) which align to form a hole for receiving the blocking component. The hole may extend in a direction parallel to a longitudinal axis (R) of the spring sleeve.