Dual-Parallel Piston Interface for LVDT Access Under Bending Loads
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Solution Overview
Problem
Fly-by-wire actuation systems in aircraft require position-sensing capability, but existing packaging arrangements for LVDTs within pistons compromise the joint's ability to withstand severe bending moments, necessitating access that weakens the piston end joint.
Innovation Solution
A dual-parallel fluid actuator apparatus with a structure that allows access to internal cavities for LVDT adjustment without compromising the joint's ability to withstand bending moments, using threaded retaining caps and anti-rotation keys to securely affix piston rods, and accommodating asynchronous piston movements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If LVDTs are arranged within a hollow piston body for position sensing, then position-sensing capability is achieved, but access to LVDT for adjustment and calibration becomes difficult without compromising the piston end joint strength
Solution Approach 1:
The piston end assembly is segmented into modular components: the piston body, end cap, and retaining cap. This segmentation allows the retaining cap to be removed for LVDT access while the main piston end joint remains intact and strong, resolving the contradiction between measurement access and structural strength.
Solution Approach 2:
The LVDT adjustment and calibration function is extracted from the main piston body by providing a separate access path through the removable retaining cap. This allows LVDT maintenance without compromising or modifying the main piston end joint structure, maintaining both strength and accessibility.
2Ease of operation
If features are added to enable access to LVDT after assembly, then ease of operation for LVDT adjustment is improved, but the piston end joint becomes weakened
Solution Approach 1:
The piston end assembly is divided into functional segments: the main joint structure and the removable retaining cap. This allows easy LVDT access through cap removal without adding features that would weaken the main joint, as the access mechanism is a separate, non-intrusive component.
Solution Approach 2:
The retaining cap is designed to be dynamically removable and reattachable, providing ease of operation for LVDT adjustment. This dynamic access method does not require permanent openings or weakened features in the main joint, preserving structural strength while enabling operational flexibility.
Data Source
AI summary
The subject matter of this specification can be embodied in, among other things, an apparatus that includes a first assembly having a first piston rod having a first rod end, a second assembly arranged substantially parallel to the first piston assembly and having a second piston rod having a second rod end, an end assembly defining a first aperture configured to receive the first rod end, and a second aperture configured to receive the second rod end, a first retaining cap configured to affix to the first rod end, abut the end assembly when affixed to the first rod end, and retain the first rod end within the first aperture, and a second retaining cap configured to affix to the second rod end, abut the end assembly when affixed to the second rod end, and retain the second rod end within the second aperture.