Valve End Cap Retention With Groove-Lock Assembly
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Solution Overview
Problem
The assembly and retention of end caps in spool valves, such as servovalves, are costly and time-consuming due to the need for substantial endplates under high pressures, which also add weight, particularly problematic in applications like aircraft.
Innovation Solution
A valve assembly with a circumferentially extending groove in the valve housing and radially outwardly extending retaining elements on the end cap, combined with an anti-rotation element and locking mechanism, allows for secure retention of the end cap without the need for endplates, using a plastics material for the anti-rotation element to reduce weight and simplify assembly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If substantial endplates with multiple bolts are used to retain end caps under high pressures, then the reliability and pressure resistance are improved, but the weight and device complexity increase significantly
Solution Approach 1:
The patent extracts and eliminates the heavy endplate component from the valve assembly. Instead of using substantial endplates with multiple bolts to retain end caps under high pressures, the invention uses a lightweight retaining ring that achieves the same retention function through a different mechanism (radially outwardly extending retaining elements engaging with radially inwardly extending retaining elements), thereby significantly reducing valve weight while maintaining pressure resistance
Solution Approach 2:
The patent inverts the traditional retention mechanism. Rather than having the end cap pushed against by a heavy endplate from the outside, the end cap is retained by radially outwardly extending retaining elements on the end cap itself engaging with radially inwardly extending retaining elements in the valve body, creating a self-retaining structure that eliminates the need for heavy endplates
2Reliability
If substantial endplates with multiple bolts are used to retain end caps, then the pressure resistance is improved, but the assembly time and manufacturing cost increase
Solution Approach 1:
The patent removes the complex endplate and multiple bolt assembly system, replacing it with a simple retaining ring mechanism that can be installed quickly by simply placing the retaining ring over the end cap, dramatically reducing assembly time and manufacturing cost while maintaining the ability to withstand high pressures
Solution Approach 2:
The patent segments the retention function into separate radial retaining elements rather than requiring a complete endplate structure. The radially outwardly extending retaining elements on the end cap engage with radially inwardly extending retaining elements in the valve body, allowing for simplified assembly without compromising pressure resistance
3Ease of manufacture
If end caps are retained with radially outwardly extending retaining elements rotating into grooves, then the assembly simplicity is improved, but rotation control and precise positioning become problematic
Solution Approach 1:
The patent uses asymmetric keyway features and corresponding key features on the retaining ring that prevent rotation of the end cap. The asymmetric geometry of the keyway and key ensures that the end cap can only be positioned in the correct orientation, providing precise positioning and rotation control while maintaining the simplicity of the snap-fit assembly mechanism
Data Source
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AI summary
A valve assembly (100) comprises a valve housing (102) having a bore (104) formed therein. The bore (104) has an axis A and comprises a circumferentially extending groove (144) formed therein at an end portion (106) thereof. An axially outer wall (146) of the groove (144) comprises at least two circumferentially spaced radially inwardly extending retaining elements (148) defining an axial slot (152) therebetween. An end cap (120) is received in the end portion (106) of the bore (104) and closes the end of the bore (104). The end cap (120) comprises a retaining portion (174) comprising at least one radially outwardly extending retaining element (176) which is shaped so as to be insertable through the axial slot (152) into the groove (144) and rotatable therein to a retaining position in which the radially outwardly extending retaining element (176) aligns with one of the radially inwardly extending retaining elements (148) to prevent axial withdrawal of the end cap (120) from the bore (104). An anti-rotation element (122) is insertable axially into the axial slot (152) after the end cap (120) has been rotated to its retaining position to prevent rotation of the end cap (120) from its retaining position to a position in which it may be withdrawn axially from the bore (104). A locking element (124) prevents withdrawal of the anti-rotation element (122) from the axial slot (152).