Capacitive Probe Fabrication via Thermal Spray Deposition
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Solution Overview
Problem
Existing proximity sensors in gas turbine engines face failure due to exposure to extreme temperatures, particularly those using adhesive or epoxy mounting methods.
Innovation Solution
A method involving the thermal spraying of non-conductive and conductive layers onto a substrate or case structure to encapsulate sensor wires, with a plasma deposition spray process, and the use of a ferrule for secure mounting, eliminating the need for adhesives and enhancing durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If adhesive or epoxy mounting methods are used for sensors, then ease of manufacture is improved, but reliability deteriorates due to failure under extreme temperatures
Solution Approach 1:
The patent replaces chemical bonding (adhesive/epoxy) with a mechanical/physical bonding system where the sensor is mounted directly to the case structure using a ferrule and retaining ring assembly. This mechanical mounting method eliminates the reliance on temperature-sensitive adhesives while providing secure attachment that can withstand extreme thermal environments.
Solution Approach 2:
The patent employs a composite mounting structure consisting of multiple materials: ferrule (metal), retaining ring (metal), and O-ring (elastomer). This composite approach combines the thermal stability of metals with the sealing properties of elastomers, creating a mounting system that is both mechanically secure and thermally resilient.
2Measurement precision
If optical fiber is mounted within static structure proximate to rotating blade, then measurement precision is improved, but object-affected harmful factors worsen due to exposure to extreme temperature environment
Solution Approach 1:
The patent uses an O-ring (flexible elastomeric component) as part of the sensor mounting assembly. This flexible element provides thermal isolation and compliance, protecting the optical fiber and electronic components from extreme temperature fluctuations while maintaining precise positioning for accurate blade tip clearance measurements.
Solution Approach 2:
The ferrule and retaining ring assembly serve as intermediary structures between the optical fiber sensor and the case structure. These intermediaries provide thermal buffering and mechanical support, allowing the sensor to maintain measurement precision while being protected from the harshest thermal environments through the mounting 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 a robust and reliable mounting structure for proximity sensors, capable of withstanding extreme temperatures, reducing the risk of failure and maintaining sensor functionality in high-temperature environments.
Implementation Method 1
depositing a base electrically non-conductive layer with a cure in place process onto the substrate and around the sensor wire; and encapsulating the sensor wire within an electrically conductive layer deposited onto the base non-conductive layer with a cure in-place process
Data Source
Figure 1
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Figure 3~4
AI summary
A proximity sensor includes a lead supported on an outer surface of a case structure and a sensor wire that extends from the lead and through an opening in the case structure. The sensor is formed by applying alternating layers of electrically conductive and non-conductive materials in a non-cured state. A base non-conductive layer is applied to an inner surface of the case structure around the sensor wire in a non-cured state. Once cured, a conductive layer is deposited onto the base non-conductive layer and encapsulates the sensor wire. A cover non-conductive layer is then deposited over portions of the conductive layer to insulate the conductive layer. Portions of the non-conductive layer are then removed such that an area of the conductive layer is exposed to define a sensor area.