Combined Pressure Temperature Sensor Diaphragm Integration
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Solution Overview
Problem
Existing combined fluid pressure and temperature sensors face limitations in response time, environmental compatibility, and manufacturing cost, particularly when exposed to corrosive media, with current solutions either having slow response times or being costly and complex to assemble.
Innovation Solution
A combined pressure and temperature sensor design featuring a variable capacitor with a flexible diaphragm and a discrete SMT NTC thermistor on the diaphragm surface, protected by a thin polymer layer, along with a fluid flow diffuser to enhance fluid flow and accuracy, positioned within a housing with a fluid pressure receiving port and annular glass seal, optimized for the 6.5 psia to 1,000 psia pressure and −40°C to 125°C temperature range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If the thermistor is coated onto the exposed face of the diaphragm, then the temperature sensor response time is reduced, but the sensor becomes more susceptible to corrosive media
Solution Approach 1:
A thin polymer film is applied over the diaphragm surface to protect the thermistor from corrosive media while maintaining thermal contact for fast response. The polymer film acts as a protective barrier that does not significantly impede heat transfer, thus preserving both corrosion resistance and response time performance.
2Ease of manufacture
If the thermistor is disposed within the fluid receiving port or beyond the port, then manufacturing cost is reduced and assembly is easier, but the sensor becomes less robust
Solution Approach 1:
The thermistor is integrated directly onto the diaphragm surface, merging the temperature sensing function with the pressure sensing structure. This integration provides robustness by securing the thermistor in a protected location while maintaining ease of manufacture through direct attachment methods, avoiding complex assembly procedures.
3Object-affected harmful factors
If a thin polymer layer is applied over the diaphragm to protect the thermistor, then environmental compatibility is improved, but thermal mass increases slightly
Solution Approach 1:
A thin polymer film is used to protect the thermistor, and its thickness is specifically controlled to minimize thermal mass addition. The film is thin enough that the increase in thermal mass is negligible for the overall sensor response characteristics, while still providing adequate protection against corrosive environments.
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 low-cost, robust sensor with improved response time and environmental compatibility, offering superior accuracy and reliability across a wide range of fluid applications while minimizing thermal mass and maintaining sensitivity.
Implementation Method 1
a change in fluid pressure causes concomitant changes in the position of the diaphragm to thereby cause change in the capacitance of the capacitor
Implementation Method 2
A temperature responsive element such as a thick film thermistor is coated onto the exposed face of the diaphragm
Data Source
AI summary
A combined fluid pressure transducer and temperature sensor (10) has a housing (12) containing a variable capacitor (14) having a rigid substrate (14a) and attached flexible diaphragm (14b) in sealed, spaced apart relation. The capacitor is mounted in the housing so that the outer face surface of the diaphragm is exposed to a fluid pressure chamber (12k). A temperature responsive sensor element (28) is disposed on the outer face surface of the diaphragm and covered by a thin protective layer. A fluid flow diffuser (30) is disposed in the fluid pressure port (12b) for directing fluid flow across the temperature sensor.