Metal Membrane Sensor Layout for Hermetic Pressure-Temperature Sensing
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Solution Overview
Problem
Current sensor arrangements for measuring pressure and temperature in fluid systems, particularly in CO2-based air-conditioning and fuel injection systems, face challenges such as complexity in production, leakage issues due to the use of elastomers, and the need for separate sensors which can lead to additional leakage problems and inaccurate fuel injection due to temperature-dependent viscosity changes.
Innovation Solution
A combined temperature and pressure sensing arrangement using a metallic membrane structure where both sensors are coupled to one side, allowing for efficient heat conduction and reduced leakage, with a metallic membrane that conducts temperature to the temperature-sensitive element and transfers pressure to the pressure-sensitive element, eliminating the need for adhesive materials and enhancing durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If separate pressure sensor and temperature sensor are used, then measurement capability is improved, but device complexity and leakage risk increase
Solution Approach 1:
The patent combines pressure sensing and temperature sensing functions into a single integrated sensor arrangement. The pressure sensor and temperature sensor are mounted on the same housing with their sensing elements positioned on opposite sides of a common diaphragm, eliminating the need for separate sensor housings and reducing overall device complexity while maintaining full measurement capability.
Solution Approach 2:
The common diaphragm serves multiple functions: it acts as the pressure-sensing element for the pressure sensor, the temperature-sensing element for the temperature sensor, and provides hermetic sealing for the fluid chamber. This multi-functional design reduces the number of components needed and simplifies the overall structure.
2Ease of manufacture
If elastic and adhesive materials are used for sealing, then ease of manufacture is improved, but reliability deteriorates due to CO2 leakage
Solution Approach 1:
The patent replaces elastic sealing materials (rubber, elastomers) with a metal diaphragm that provides hermetic sealing through its rigid structure. The diaphragm is welded to the housing, creating a permanent metallurgical bond that is immune to the chemical effects of CO2 that degrade adhesive and elastomeric seals, thereby ensuring long-term reliability and hermeticity.
3Strength
If adhesive seals are used to decouple mechanical stress, then protection of sensors is improved, but manufacturing complexity increases
Solution Approach 1:
The patent extracts the stress-decoupling function from the adhesive layer and transfers it to a dedicated mechanical element - a support ring or flange structure. This rigid element mechanically isolates the sensor mounting surfaces from pressure-induced deformations of the housing, providing sensor protection through structural design rather than relying on adhesive properties.
4Productivity
If response time is reduced for dynamic measurement, then productivity is improved, but measurement precision may worsen due to thermal mass
Solution Approach 1:
The patent applies local quality by making the diaphragm thin in the regions where temperature and pressure sensing elements are positioned, while maintaining sufficient thickness in other areas for structural integrity. This localized thinning reduces thermal mass and improves response time without compromising the overall strength and hermeticity of the sensor housing.
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 compact, accurate, and reliable sensor arrangement capable of measuring high pressures and temperatures, reducing leakage risks and improving dynamic response, suitable for systems operating up to 200 bar and -40°C to 180°C, while maintaining hermeticity and extending the sensor's lifespan.
Implementation Method 1
the membrane structure is arranged to pass on the temperature of the fluid which is at the other side of the membrane structure, to the temperature sensitive electrical element
Implementation Method 2
to transfer the pressure in the fluid to the pressure sensing electrical element
Data Source
AI summary
A sensor arrangement (1) for measuring a pressure and a temperature in a fluid is disclosed. The sensor arrangement (1) comprises a temperature sensitive electrical element (3) and a pressure sensing electrical element (6), the temperature sensitive electrical element (3) and pressure sensing electrical element (6) are both coupled to one side of a metallic membrane structure (4,16). The metallic membrane structure is arranged to pass on the temperature of the fluid which is at the other side of the membrane structure (4,16) to the temperature sensitive electrical element (3) and to pass on the pressure in the fluid to the pressure sensing electrical element (6). In this way a combined pressure and temperature sensor is obtained which is applicable in vehicle air-conditioning systems working with CO2 as refrigerant.