Dual-Load-Path Actuator Verification Through Backlash Measurement
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Solution Overview
Problem
Existing actuators lack a clear indication of component failure and can be difficult to diagnose, which poses challenges in ensuring the reliability of systems like aircraft components.
Innovation Solution
The actuator design includes a primary and secondary load path with a ball screw, ball nut, and a rotating member, where a method is implemented to verify the actuator's functionality by measuring torque and rotational angles to determine backlash, allowing for detection of potential failures and switching to a secondary load path if necessary, with an electronic control unit monitoring and reporting any malfunctions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single load path is used in the actuator, then the device complexity is reduced, but the reliability decreases because there is no backup path when components fail
Solution Approach 1:
The actuator is divided into two independent load paths: a primary load path (ball screw, ball nut, extension tube) and a secondary load path (rod with threaded portion, rotating member). This segmentation allows the system to maintain functionality through the secondary path when the primary path fails, resolving the contradiction between reliability and complexity by organizing redundant components into distinct functional segments.
Solution Approach 2:
The secondary load path is designed as a pre-prepared backup system that remains dormant during normal operation but can immediately engage when the primary load path fails. The rod and rotating member are positioned and configured in advance to provide immediate support, cushioning against the harmful effect of primary path failure and maintaining system reliability without requiring complex real-time switching mechanisms.
2Difficulty of detecting and measuring
If no verification method is implemented, then the ease of operation is improved, but the difficulty of detecting and measuring component failures increases
Solution Approach 1:
The actuator incorporates a feedback mechanism where the electronic control unit monitors the relationship between motor rotation and end fitting movement. By comparing expected versus actual positional feedback, the system can detect failures in the primary load path components (ball screw, ball nut, extension tube) and automatically switch to the secondary load path, making failure detection straightforward without complicating the operational interface.
Solution Approach 2:
The system performs preliminary verification of the secondary load path by manually rotating the input portion to check for proper engagement of the rod and rotating member before normal operation begins. This preliminary action ensures the backup path is functional and ready, simplifying ongoing operation by eliminating the need for complex real-time diagnostics during normal use.
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
This solution enables reliable operation by providing a clear indication of primary load path failures and ensuring continued functionality through the secondary load path, enhancing the reliability and safety of systems like aircraft components.
Implementation Method 1
a ball screw connected to the end fitting, a ball nut engaged with the ball screw
Implementation Method 2
the rod including a threaded portion, and/or a rotating member engaged with the rod
Data Source
AI summary
An actuator includes an end fitting, a ball screw connected to the end fitting, a ball nut engaged with the ball screw, a rod disposed at least partially within the ball screw, and a rotating member engaged with the rod. A method of verifying an actuator may include rotating a manual input portion in a first direction under substantially no load until the manual input portion stops, rotating the manual input portion in a second, opposite direction until a first torque is measured, determining a first rotational angle at which the first torque was measured, rotating the manual input portion in the first direction until a second torque is measured, determining a second rotational angle at which the second torque was measured, and verifying a second load path if a backlash is within a predetermined range.