Servo-Valve Rotor Stop Detection for Failure Monitoring
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Solution Overview
Problem
Conventional servo-valves with mechanical feedback require bulky and costly linear variable differential transformer (LVDT) sensors for position monitoring, increasing size, weight, cost, and reducing reliability, particularly problematic in aviation applications.
Innovation Solution
A method using simple stop-engagement detectors, such as dry contacts or contactless sensors, to detect the rotor engaging a stop and generate a malfunction signal, reducing the need for bulky sensors and improving reliability and cost-effectiveness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If LVDT sensors are used for position monitoring, then measurement precision is improved, but device complexity and weight increase
Solution Approach 1:
The patent extracts the monitoring function from complex LVDT sensors and implements it through simple stop-engagement detectors that only need to detect whether the rotor has engaged a stop position. This eliminates the need for continuous position measurement while retaining failure detection capability.
Solution Approach 2:
The patent replaces expensive, complex LVDT sensors with inexpensive, simple stop-engagement detectors (such as dry contacts or contactless sensors). These simple detectors are sufficient for the specific task of detecting rotor stop engagement, providing cost-effective monitoring without the overhead of precision measurement systems.
2Measurement precision
If LVDT sensors are used for position monitoring, then measurement precision is improved, but weight increases
Solution Approach 1:
The patent removes the heavy LVDT sensor components and retains only the essential monitoring function through lightweight stop-engagement detectors. This extraction eliminates unnecessary weight while preserving the critical failure detection capability.
Solution Approach 2:
The patent substitutes heavy, precision measurement equipment with lightweight, simple detectors that are adequate for the specific monitoring need. This substitution dramatically reduces weight while maintaining sufficient monitoring precision for safety-critical failure detection.
3Measurement precision
If LVDT sensors are used for position monitoring, then measurement precision is improved, but cost increases
Solution Approach 1:
The patent replaces expensive LVDT sensors with inexpensive stop-engagement detectors such as dry contacts or simple contactless sensors. This substitution maintains adequate monitoring precision while dramatically reducing component cost and simplifying manufacturing.
Solution Approach 2:
The patent extracts only the essential failure detection function from the expensive LVDT sensor system, implementing it through minimalistic stop-engagement detectors. This extraction eliminates costly components while retaining the core safety monitoring capability.
4Reliability
If LVDT sensors are used for position monitoring, then reliability is improved, but device complexity increases
Solution Approach 1:
The patent enables the rotor to self-indicate its state through physical stop engagement, which automatically triggers the detection mechanism. This self-service approach eliminates the need for complex active sensing systems while maintaining reliable failure detection, as the system monitors its own state through the mechanical feedback already present.
Data Source
AI summary
A method of detecting failure of a two-stage servo-valve in which the power-controlling movable member is connected to the rotor of a torque motor of a pilot stage by mechanical feedback. A malfunction signal is generated in response to detecting that the rotor of the torque motor has engaged a stop. The invention also provides a servo-valve for implementing such a method.