Dielectric Washer Isolation for High Voltage Thin Film Sensors
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Thin film pressure sensors in aircraft systems face challenges with high voltage inputs from lightning strikes and harsh environmental conditions, such as high pressures and temperatures, which can lead to sensor failure, and existing sensors are not adequately protected or insulated to withstand these conditions.
Innovation Solution
The use of dielectric isolation washers, such as Torlon, Zirconia, and Nylon, between the pressure sensor and the metal housing to prevent voltage transmission and provide electrical insulation, allowing the sensor to 'float' within the housing without metal-to-metal connections, thereby increasing the dielectric rating to 1500 VAC and enhancing durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a metal thin film sensor is used with direct metal housing and diaphragm construction, then the sensor can measure high pressure and is mechanically robust, but the sensor cannot withstand high voltage inputs (1500 VAC) due to conductive metal components
Solution Approach 1:
A dielectric washer is introduced as an intermediary component between the metal sensor assembly and the metal housing. This non-conductive washer prevents direct electrical contact while allowing mechanical support, thereby enabling the sensor to withstand high voltage inputs (1500 VAC) while maintaining the mechanical robustness of the metal construction.
Solution Approach 2:
The sensor assembly combines metal components (housing, diaphragm, strain gauge) with a dielectric material (washer). This composite structure allows the metal parts to provide mechanical strength and pressure transmission while the dielectric material provides electrical insulation, resolving the contradiction between mechanical robustness and voltage withstand capability.
2Reliability
If dielectric isolation washers are added to provide electrical insulation, then the dielectric rating increases to 1500 VAC, but the device complexity increases
Solution Approach 1:
The dielectric isolation function is achieved through a simple segmented structure using a washer component. This segmentation approach provides effective electrical insulation (1500 VAC rating) without requiring complex multi-layer insulation assemblies or additional sophisticated components, thus minimizing the increase in device complexity.
3Reliability
If the sensor is mounted with metal-to-metal connections to the housing, then the sensor is mechanically secured, but the sensor is exposed to high voltage inputs from lightning strikes
Solution Approach 1:
The dielectric washer serves as a mediator that maintains mechanical mounting functionality while providing electrical protection. The washer allows the sensor to be securely mounted to the metal housing while blocking the transmission of high voltage inputs from lightning strikes, thus protecting the sensor without complicating the mounting process.
Solution Approach 2:
The dielectric washer is pre-installed between the sensor and housing to prevent high voltage inputs from reaching the sensor before a lightning strike occurs. This preliminary protective measure ensures that when voltage spikes occur, the sensor is already protected by the insulating barrier, eliminating the need for complex active protection systems.
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 effectively protects thin film pressure sensors from high voltage inputs and extreme conditions, providing a higher dielectric rating and improved stability at extreme temperatures, making them more suitable for aircraft applications compared to MEMS sensors.
Implementation Method 1
dielectric isolation washers are provided between the pressure sensor that senses the system pressure and the interior surfaces of the exterior metal housing... the dielectric washers isolate the metal thin film pressure sensor from all adjacent metal components in the assembly with non-conducting insulating materials
Implementation Method 2
Both types use piezoresistive strain gauges to convert pressure into an electrical output... A metal thin film sensor uses changes in resistance in a Wheatstone bridge strain gauge structure, due to the metal diaphragm deflection, to measure pressure
Data Source
AI summary
Improvements in thin film sensors are disclosed. These can be used for aircraft applications. Dielectric isolation washers can be provided between a pressure sensor and an exterior metal housing of a sensor assembly. In this manner, high voltage inputs from a lightning strike or other source that reach the sensor housing are not transmitted to the sensor. Dielectric washers, insulators, and potting compounds can thus isolate a metal thin film pressure sensor from adjacent metal components (e.g., using non-conducting insulating materials like Torlon, zirconia and nylon). Besides their high dielectric strength, these materials exhibit compressive strength and resistance to wear, creep and corrosion. Desirable thicknesses for these components are provided. The described thin film pressure sensor embodiments can attain a dielectric rating of 1500 VAC.