Metal Measuring Diaphragm Pressure Sensor for Extreme Cold
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Solution Overview
Problem
Existing pressure sensors are limited to temperatures above -70°C due to the use of pressure-transmitting liquids and mechanical sensitivity, which restricts their application in extreme low-temperature environments such as natural gas liquefaction and liquefied natural gas transport.
Innovation Solution
A solid metallic pressure sensor with a metal measuring diaphragm and electromechanical converter, where the measuring diaphragm is made of a material with high percentage elongation, such as titanium or tantalum alloys, and an insulator with a thermal expansion coefficient matching the sensor body, allowing operation below -70°C without mechanical tension.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If pressure-transmitting liquids are used in pressure sensors, then the sensors can operate at higher temperatures, but they cannot be used below the freezing point of the fluid
Solution Approach 1:
The invention removes the pressure-transmitting liquid from the sensor system entirely, using a solid metallic diaphragm that can be directly exposed to the medium. This extraction of the fluid component eliminates the freezing temperature limitation while maintaining pressure transmission capability through the solid diaphragm structure.
Solution Approach 2:
The invention replaces the hydraulic/mechanical system using pressure-transmitting fluid with a direct solid metallic diaphragm structure. The diaphragm itself becomes the pressure transmission element, eliminating the need for intermediate fluid coupling and extending operational temperature range.
2Reliability
If elastomers are used to clamp the measuring diaphragm, then mechanical stresses are prevented, but the elastomers fail at low temperatures below -70°C
Solution Approach 1:
The invention changes the material parameter of the clamping element from elastomer to metal, fundamentally altering the material's temperature-dependent properties. The metallic clamping element maintains its mechanical properties at low temperatures where elastomers would fail, enabling operation below -70°C.
Solution Approach 2:
The invention uses a composite construction where the metallic clamping element integrates with the sensor body and diaphragm structure. This composite metallic structure provides both the necessary clamping function and low-temperature reliability that single-material elastomer solutions cannot achieve.
3Ease of manufacture
If the measuring diaphragm is clamped directly in the sensor housing, then mounting is simplified, but mechanical stresses arise in the diaphragm area
Solution Approach 1:
The invention segments the sensor structure into distinct functional zones: the clamping area in the sensor housing and the measurement area of the diaphragm. By separating these functions spatially and structurally, the design allows direct clamping mounting while preventing stress transmission to the measurement region, maintaining both manufacturing simplicity and measurement reliability.
4Adaptability or versatility
If titanium disc is used as measuring diaphragm, then direct exposure to pressure is enabled, but the disc cannot absorb thermal expansion forces at low temperatures
Solution Approach 1:
The invention uses homogeneous metallic material (titanium or titanium alloy) for both the diaphragm and the sensor body. This material homogeneity ensures compatible thermal expansion characteristics, allowing the diaphragm to directly expose to pressure while the entire metallic structure collectively absorbs thermal expansion forces without creating differential stress.
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
Enables accurate pressure measurement at temperatures as low as -165°C without mechanical tension in the measuring diaphragm, ensuring reliable operation in extreme cold conditions.
Implementation Method 1
a pressure-dependent elastically deformable metallic measuring diaphragm arranged on the front side of the sensor body
Implementation Method 2
an insulator with a thermal expansion coefficient matching the sensor body
Data Source
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AI summary
A pressure sensor comprising: a solid metal sensor body, having a front region and a base adjoining thereto, which has an outer edge, which can be clamped by means of a fastening device; a recess, which is provided in the front region and is open towards a front side of the front region that faces away from the base; a metal measuring diaphragm, to which a pressure is applied from outside during measurement operation and which can be deformed elastically depending upon the pressure, is arranged on the front side of the sensor body, closes off the recess from the outside, and is spaced apart from the outer edge of the front region; and an electromechanical transducer for detection, by means of measuring the pressure-dependent deformation of the measuring diaphragm, having at least one measuring element, which is electrically insulated from the measuring diaphragm and the sensor body by means of an insulating element.