Servovalve Filter Retaining Plug for Damage-Free Screen Replacement
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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 design with evenly distributed annular slots and a corresponding tool with chamfered edges and a rotating mechanism allows for easy removal of the plug from the servovalve port without applying damaging forces, facilitating the replacement of filter screens.
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 servovalve port, but the plug becomes difficult to remove and may cause damage to the servovalve body
Solution Approach 1:
The plug is segmented with radially extending slots that divide the plug body into sections. These slots allow a removal tool to engage with the plug and apply controlled extraction forces, enabling easy removal while maintaining secure retention during normal operation.
Solution Approach 2:
A removal tool acts as an intermediary between the operator and the plug. The tool engages with the slots in the plug and applies controlled forces to extract the plug without damaging the servovalve body, mediating between the need for secure retention and easy removal.
2Strength
If the plug is tightly press-fitted to secure the filter, then retention is strong, but removal requires excessive force that may damage the servovalve port
Solution Approach 1:
The slots segment the plug structure, allowing removal forces to be distributed across multiple engagement points. This segmentation enables controlled extraction that prevents concentration of excessive forces on any single point of the servovalve port.
Solution Approach 2:
The plug design changes the mechanical parameters of force distribution during removal. By incorporating slots that engage with a removal tool, the force application method changes from direct pulling (which concentrates stress) to distributed extraction through multiple contact points, reducing harmful stresses on the servovalve body.
3Reliability
If the filter screen is retained by a press-fitted plug, then filtration is effective, but maintenance and replacement of the filter screen becomes difficult and time-consuming
Solution Approach 1:
The segmented plug design with slots enables quick engagement with a removal tool, significantly reducing the time required to remove and replace the filter screen while maintaining effective filtration during operation.
Solution Approach 2:
The plug design enables easy maintenance by allowing operators to quickly remove and replace filter screens using a simple removal tool, making the maintenance process self-serviceable without requiring specialized equipment or extensive time investment.
Data Source
Figure 1~2
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Figure 5~6
AI summary
A plug (20) for retaining a filter screen (14) in a fluid port (10) of a servovalve (2), the plug (20) comprises an annular body (22). The annular body (22) comprises opposed first and second axial annular end surfaces (24, 26). A radially inner surface (28) extendes between the first and second axial annular end surfaces (24, 26) and a radially outer surface (30) extends between the first and second axial annular end surfaces (24, 26). At least one recess (36) is formed in the radially inner surface (28) for receiving a tool (50) for removing the plug (20) from the port (10). A plurality of slots (25) is formed in the first axial annular end surface (24) and extends into the at least one recess (36) for providing access for the tool (50) to the at least one recess (36).