Lost-Motion Actuator Assembly for Seal Stability Under Relative Loads
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Solution Overview
Problem
Gas turbine engine actuators face challenges due to relative motion and loads between the nacelle and fan case, which affect sealing performance, necessitating a more robust actuator design.
Innovation Solution
The actuator assembly incorporates a housing, piston rod, and a lost motion device with a slider, biasing member, and sealing members to mitigate these loads and improve sealing efficiency, featuring a flared housing portion and a hydraulic sealing groove to enhance sealing and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional actuator design is used, then the structure is simple, but the sealing performance deteriorates under relative motion and loads
Solution Approach 1:
The lost motion device is nested within the actuator housing, with the slider positioned inside the housing bore and the piston rod extending through it. This nested arrangement allows the lost motion device to be integrated into the existing actuator structure without requiring separate external components, thereby improving sealing performance while minimizing additional complexity
Solution Approach 2:
The lost motion device acts as an intermediary mechanism between the piston rod and the actuator housing. It absorbs relative motion and loads through the slider's movement within the housing bore, protecting the sealing members from direct exposure to these adverse conditions and maintaining sealing performance
2Reliability
If the actuator is made more robust to resist relative motion and loads, then sealing performance improves, but device complexity increases
Solution Approach 1:
The actuator assembly is segmented into distinct functional components: the housing, piston rod, and lost motion device with slider. This segmentation allows the lost motion device to specifically address relative motion and load resistance, while other components maintain their original simple designs, achieving robustness without overall complexity increase
Solution Approach 2:
The lost motion device provides beforehand cushioning by absorbing relative motion and loads before they can affect the sealing members. The slider's ability to move within the housing bore creates a cushioning effect that protects the actuator assembly from adverse conditions, improving reliability without requiring a completely redesigned robust structure
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 improved sealing performance and resistance to relative motion and loads, ensuring reliable operation and reduced leakage in gas turbine engine maintenance scenarios.
Implementation Method 1
a biasing member that is disposed within the piston bore and engages a first spring seat that is secured within the piston bore between the first piston end and the second piston end and engages a second spring seat that is disposed proximate the first piston end
Implementation Method 2
a sealing member is disposed about the piston rod and is engaged with the housing bore proximate the first housing end
Data Source
AI summary
An actuator assembly includes a housing, a piston rod, and a lost motion device. The housing defines a housing bore that extends along a first axis from a first housing end towards a second housing end. The piston rod is at least partially disposed within the housing bore. The piston rod defines a piston bore that extends from a first piston end towards a second piston end along the first axis. The lost motion device is at least partially disposed within the housing bore and extends into the piston bore. The lost motion device and the piston rod are arranged to move relative to the housing along the first axis.