Servovalve Filter Retaining Plug With Recessed Removal Interface
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Solution Overview
Problem
Servovalves in aircraft control systems face difficulties in removing and replacing filter screens due to press-fitted plugs, which can cause damage to the servovalve body, necessitating costly repairs.
Innovation Solution
A plug with an annular body featuring a recess for tool engagement, allowing for easy removal and replacement, combined with a specialized tool for gripping and extracting the plug, facilitating the maintenance of servovalves without damaging them.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a press-fitted plug is used to retain the filter screen, then the filter screen is securely retained in the port, but the plug becomes difficult to remove and may cause damage to the servovalve body
Solution Approach 1:
The plug is segmented into a body portion and a tool engagement portion (recess), allowing the retention function to be separated from the removal function. The recess provides a specific interface for tool engagement, enabling the plug to be removed without damaging the servovalve body while maintaining secure filter screen retention during operation.
Solution Approach 2:
A specialized removal tool acts as an intermediary between the operator and the plug. The tool engages with the recess in the plug, transferring force in a controlled manner to remove the plug without causing damage to the servovalve body. This intermediary mechanism resolves the contradiction by providing a controlled removal path.
2Reliability
If the filter screen is retained by a press-fitted plug, then the filter screen is securely held in place, but removal and replacement of the filter screen becomes difficult and time-consuming
Solution Approach 1:
The plug design segments the retention mechanism (press-fit body) from the removal mechanism (recess), allowing rapid tool engagement and removal. This segmentation enables quick filter screen replacement while maintaining secure retention during operation, directly addressing the time loss issue.
Solution Approach 2:
The recess is pre-formed in the plug during manufacturing, preparing the interface for tool engagement in advance. This preliminary action ensures that when removal is needed, the tool can immediately engage with the recess without requiring additional preparation steps, reducing overall replacement time.
3Reliability
If the plug is interference fitted in the port to retain the filter screen, then secure retention is achieved, but the servovalve body may require repair if damage occurs during removal
Solution Approach 1:
The removal tool serves as an intermediary that controls the force application during plug removal. By engaging with the recess, the tool distributes and controls the extraction forces, preventing damage to the servovalve body while still enabling removal of the interference-fitted plug.
Solution Approach 2:
The plug includes a self-contained recess feature that automatically provides the necessary interface for tool engagement. This self-service design ensures that the plug carries its own removal mechanism, eliminating the need for external damage to the servovalve body during removal operations.
Data Source
AI summary
A plug for retaining a filter screen in a fluid port of a servovalve, comprises an annular body, the annular body comprising: opposed first and second axial end surfaces, a radially inner surface extending between the first and second axial end surfaces, a radially outer surface extending between the first and second axial end surfaces and at least one recess formed in the radially inner surface for receiving a tool for removing the plug from the port. A tool for removing the plug comprises a pair of handles pivotally mounted to one another about a pivot, each handle having a plug gripping portion extending therefrom beyond the pivot, each plug gripping portion comprising an outwardly projecting tooth for engaging in the recess of the plug when the plug gripping portions are moved apart by operation of the handles.