Three-Spring Ram Air Turbine Actuator for Uplock Hook Vibration

Solution Overview

Problem

Traditional ram air turbine (RAT) actuators suffer from vibratory impacting of the uplock hook during stowed position, leading to potential damage, and enlarging the actuator to provide greater force is not feasible due to weight and performance restrictions.

Innovation Solution

The use of three biasing members - a disk spring stack, a helical spring, and another helical spring - positioned radially within the actuator housing to provide staged forces that retain the RAT against the uplock hook, preventing vibrational damage by maintaining contact under vibrational loads.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Force

If the actuator is enlarged to provide greater force, then the force to overcome door and inertial loads is improved, but the weight and size increase which violates weight restrictions and performance requirements

Engineering Contradiction:

Improveforce to overcome door and inertial loadsVSAvoidactuator weight

Core Design Contradiction:

ForceVSWeight of moving object

Solution Approach 1:

The actuator is divided into three distinct biasing members (first biasing member for first stage, second biasing member for second stage, third biasing member for third stage) that operate in sequence. Each biasing member provides force for a specific portion of the deployment stroke, allowing the actuator to deliver high force when needed without requiring all components to be oversized throughout the entire operation, thus reducing overall weight while maintaining necessary force levels.

Inventive Principle:

Principle #1Segmentation

2Force

If the actuator is enlarged to provide greater force, then the force to overcome door and inertial loads is improved, but the volume and dimensions increase which violates performance requirements for deployment speed

Engineering Contradiction:

Improveforce to overcome door and inertial loadsVSAvoidactuator volume

Core Design Contradiction:

ForceVSVolume of moving object

Solution Approach 1:

The actuator is divided into three distinct biasing members (first biasing member for first stage, second biasing member for second stage, third biasing member for third stage) that operate in sequence. Each biasing member provides force for a specific portion of the deployment stroke, allowing the actuator to deliver high force when needed without requiring all components to be oversized throughout the entire operation, thus reducing overall volume while maintaining necessary force levels.

Inventive Principle:

Principle #1Segmentation

3Device complexity

If traditional single-stage actuators are used, then the structure is simple, but vibratory impacting of the uplock hook occurs causing potential damage

Engineering Contradiction:

Improveactuator structure complexityVSAvoiduplock hook integrity

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The actuator is divided into three distinct biasing members (first biasing member for first stage, second biasing member for second stage, third biasing member for third stage) that operate in sequence. Each biasing member provides force for a specific portion of the deployment stroke, allowing the actuator to deliver high force when needed without requiring all components to be oversized throughout the entire operation, thus reducing overall weight while maintaining necessary force levels.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The actuator employs a dynamic, multi-stage force delivery system where the three biasing members engage and disengage at different positions during the deployment stroke. This dynamic operation allows the actuator to provide high force only when necessary (during specific stages) rather than continuously, reducing vibratory impacting on the uplock hook while maintaining reliability and preventing damage.

Inventive Principle:

Principle #15Dynamics

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 configuration ensures the RAT remains securely engaged with the uplock hook, eliminating vibrational damage while meeting size, weight, and performance requirements, allowing for efficient deployment under various conditions.

Implementation Method 1

a first biasing member, a second biasing member, and a third biasing member positioned and configured to bias the actuator rod relative to the actuator housing

Methodology Applied

Scientific EffectElasticity: Elasticity

Implementation Method 2

The first biasing member can be a disk spring stack, the second biasing member can be a helical spring, and the third biasing member can be a helical spring

Methodology Applied

Scientific EffectSpring: Spring

Data Source

PatentUS10676201B2Three-spring ram air turbine actuator

Publication Date: 2020.06.09 HAMILTON SUNDSTRAND CORP

AI summary

A ram air turbine (RAT) actuator can include an actuator housing, an actuator rod configured to move relative to the actuator housing through several positions, and a first biasing member, a second biasing member, and a third biasing member positioned and configured to bias the actuator rod relative to the actuator housing. The first biasing member biases the actuator rod from a first position through a second position, the second biasing member biases the actuator rod from the first position through a third position, and the third biasing member biases the actuator rod from the first position through a fourth position. The three biasing members can be configured to bias a ram air turbine against an uplock hook with sufficient force to eliminate vibrational damage to the uplock hook while in the first position.