Near Net Shape Sintered Ceramic Pressure Sensor
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Solution Overview
Problem
Capacitive pressure sensors face challenges in measuring corrosive fluids due to errors introduced by isolation techniques and high costs associated with machining and oil fill volumes, particularly in differential pressure sensing applications.
Innovation Solution
The use of near net shape sintered ceramics for cell bodies and diaphragms with incorporated metallic parts and capacitive components, allowing for reduced oil fill volumes and eliminating the need for isolation diaphragms, along with the option to integrate temperature sensors and achieve smaller sensor sizes through advanced ceramic processing and assembly techniques.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If isolation diaphragms and oil fills are used to measure corrosive fluids, then the sensor can measure pressure of corrosive fluids, but measurement errors are introduced
Solution Approach 1:
The patent removes the isolation diaphragm and oil fill from the pressure sensor system. By fabricating the sensor directly from corrosive-resistant sintered ceramic materials, the need for isolation components is eliminated, allowing direct contact with corrosive fluids without introducing measurement errors associated with isolation techniques.
Solution Approach 2:
The patent employs sintered ceramic composite materials that combine corrosive resistance with mechanical properties suitable for pressure sensing. These ceramic materials replace the traditional combination of metal sensors isolated by diaphragms and oil fills, providing both corrosion resistance and measurement accuracy.
2Manufacturing precision
If traditional machining operations are used to fabricate sensor components, then precise dimensions can be achieved, but fabrication costs increase significantly
Solution Approach 1:
The patent incorporates all necessary features, including threaded holes for metallic parts and capacitive component structures, directly into the ceramic green body before firing. This preliminary formation of features eliminates the need for post-firing machining operations, significantly reducing fabrication costs while maintaining dimensional accuracy.
Solution Approach 2:
The patent changes the manufacturing approach from mechanical machining to ceramic sintering processes. By controlling parameters such as green body density, sintering temperature, and atmospheric conditions, precise dimensions are achieved through the sintering process itself rather than subsequent machining.
3Adaptability or versatility
If larger oil fill volumes are used in differential pressure sensors, then the sensor can accommodate isolation components, but sensor size increases
Solution Approach 1:
The patent eliminates the oil fill and isolation diaphragm components from differential pressure sensors. By using corrosive-resistant sintered ceramic materials for all components, the sensor can directly sense differential pressure in corrosive fluids without requiring volume for oil fill or isolation mechanisms, significantly reducing overall sensor size.
4Strength
If metallic parts are added after ceramic firing, then material properties are maintained, but additional manufacturing steps are required
Solution Approach 1:
The patent incorporates metallic parts into the ceramic green body before firing, along with forming the capacitive sensor structures. This preliminary integration allows the ceramics to be fired to achieve desired material properties while the metallic parts are already in position, eliminating subsequent assembly steps and reducing manufacturing complexity.
Data Source
AI summary
A capacitive pressure sensor is formed with sensor body and diaphragm components made of near net shapeable sintered ceramic. In one configuration, the differential pressure sensor has two sintered ceramic cell halves with an internal sintered ceramic diaphragm captured between the two cell halves. In another configuration, two side-by-side sintered ceramic cell halves have individual sintered ceramic diaphragms, and the chambers of the two cell halves are connected by metal tubing.