Vane Arm Assembly Redundant Axial Retention Clip
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Solution Overview
Problem
Existing gas turbine engines with variable vane arrangements face issues with the secure retention of vane arms, as fasteners can loosen during operation, leading to unexpected closure of stator vanes and undesirable excitation.
Innovation Solution
A retention clip assembly with a resilient material design, featuring a clip aperture with linear and curved wall segments, angled faces on the vane stem, and a lock nut, which provides redundant axial retention by rotating from an unlocked to a locked position, ensuring the vane arm is securely fastened.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single fastener (lock nut) is used to secure the vane arm to the vane stem, then the device complexity is reduced, but the reliability of retention deteriorates because the fastener can loosen during operation
Solution Approach 1:
The retention system is segmented into two independent components: a lock nut for primary retention and a retention clip for secondary retention. This segmentation allows each component to perform its specific function independently, preventing complete failure if one component loosens or fails during operation.
Solution Approach 2:
The retention clip is pre-installed in a first position where it does not interfere with assembly, allowing the lock nut to be installed first. The clip then rotates to a second position to engage with the vane arm, providing backup retention before operation begins. This preliminary positioning ensures that if the lock nut fails, the clip is already in place to prevent catastrophic failure.
2Reliability
If a retention clip with rotating mechanism is added to provide redundant retention, then the reliability of vane arm retention is improved, but the device complexity increases
Solution Approach 1:
The retention clip is designed to rotate automatically from the first position to the second position during assembly without requiring separate actuation. The clip's own installation process drives the rotation mechanism, and once in the second position, it self-locks to engage with the vane arm, providing redundant retention without adding complex control systems.
3Ease of operation
If the retention clip is designed with resilient material and rotating mechanism, then the ease of operation during assembly is improved, but the manufacturing precision requirements increase
Solution Approach 1:
The retention clip is made from resilient material that can elastically deform during assembly. This allows the clip aperture to temporarily accommodate misalignments between the vane stem and vane arm during the rotation from first to second position. Once assembled, the resilient material springs back to maintain precise engagement, reducing manufacturing precision requirements while facilitating easy assembly.
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 reliable and efficient retention of vane arms, preventing unexpected closure and enhancing operational stability by ensuring the vane arms remain securely attached even if the lock nut is damaged or disengaged, thus maintaining power efficiency and stability.
Implementation Method 1
The at least one clip arm or each of the pair of clip arms may be formed of a resilient material. The entire retention clip may be formed of a resilient material.
Data Source
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AI summary
A vane arm assembly (100) for a gas turbine engine (20) includes a vane stem (108) having a circumferential groove (120) axially spaced from an outer end of the vane stem. The assembly also includes a vane arm (102) defining an arm aperture (140) that the vane stem is disposed within. The assembly further includes a mechanical fastener (112) retaining an axial position of the vane arm in the axial direction. The assembly yet further includes a retention clip (114) having a base portion (126) and at least one clip arm (128), the base portion defining a clip aperture (130) that the vane stem is disposed within, the base portion disposed within the circumferential groove of the vane stem to couple the retention clip to the vane stem, the at least one clip arm including a retention member (168) engaged with the vane arm to provide redundant axial retention of the vane arm.