U-Shaped Membrane Assembly for Combustion Pressure Sensors
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Solution Overview
Problem
Pressure sensors in combustion chambers of internal combustion engines face damage from media penetrating the glow plug due to temperature and chemical properties, leading to measurement errors and reduced service life due to cyclic stress and thermal shock effects.
Innovation Solution
A ring-shaped, U-shaped membrane assembly with radially inner and outer support components provides geometric stability and flexible design, sealing the pressure chamber from combustion pressure while minimizing deformation and stress, ensuring a durable and accurate pressure measurement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a flame retardant membrane is used to seal the pressure sensor from combustion media, then the sensor is protected from temperature and chemical damage, but the membrane undergoes cyclic stress and thermal shock leading to deformation and measurement errors
Solution Approach 1:
The membrane is divided into multiple functional zones: a deformation zone that absorbs thermal stress and cyclic loading, and a rigid support zone that maintains geometric stability. This segmentation allows the membrane to simultaneously protect the sensor while maintaining measurement accuracy by preventing excessive deformation.
Solution Approach 2:
The membrane employs a composite structure combining materials with different mechanical properties - a flexible deformation region made of stress-resistant material and a rigid support region providing structural stability. This composite design enables the membrane to withstand thermal shock and cyclic stress without compromising measurement precision.
2Manufacturing precision
If the membrane is made rigid to maintain geometric stability, then measurement accuracy is improved, but the membrane cannot accommodate thermal expansion and cyclic stress
Solution Approach 1:
The membrane structure is segmented into a rigid support region that maintains geometric stability for accurate measurements and a flexible deformation region that accommodates thermal expansion and cyclic stress. This segmentation resolves the contradiction by assigning different functional requirements to different parts of the same component.
Solution Approach 2:
Different regions of the membrane have different mechanical properties: the support region is designed with high rigidity to maintain geometric stability, while the deformation region is designed with higher flexibility to absorb thermal and mechanical stresses. This local differentiation of material properties allows the membrane to simultaneously achieve geometric stability and stress resistance.
3Reliability
If the membrane is made flexible to accommodate thermal shock, then stress resistance is improved, but geometric stability deteriorates leading to measurement errors
Solution Approach 1:
The membrane is segmented into a flexible deformation zone that absorbs thermal shock and a rigid support zone that maintains geometric stability. The segmentation allows each region to perform its specialized function without compromising the other.
Solution Approach 2:
The membrane exhibits local quality differentiation where the deformation region has high flexibility for stress accommodation while the support region has high rigidity for geometric stability. This local property variation enables the membrane to simultaneously achieve stress resistance and measurement accuracy.
4Device complexity
If a simple membrane design is used, then device complexity is reduced, but the membrane cannot effectively distribute loads and prevent deformation
Solution Approach 1:
The membrane is segmented into distinct functional regions (deformation zone and support zone) that work together to distribute loads effectively. This segmentation adds some structural complexity but significantly improves load distribution and deformation control compared to a simple uniform membrane.
Solution Approach 2:
The membrane uses a composite structure with different material properties in different regions, enabling effective load distribution across the membrane surface. The composite design allows the deformation region to absorb stress while the support region maintains structural integrity, achieving reliable load distribution.
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 membrane assembly effectively seals the pressure sensor from combustion media, reducing deformation and stress, thereby enhancing the service life and accuracy of pressure measurements by distributing loads and preventing thermal shock effects.
Implementation Method 1
a spring-elastic membrane (1), which comprises a pressure-loaded area (11) on which the pressure (p) prevailing in the combustion chamber mainly acts during operation of the internal combustion engine
Implementation Method 2
a spring-elastic membrane (1) configured in a U-shape in section, which comprises a pressure-loaded area (11) on which the pressure (p) prevailing in the combustion chamber mainly acts
Data Source
Figure 1
Figure 2
Figure 3a~3b
AI summary
The invention relates to a membrane assembly for a pressure measuring device for determining a pressure in a combustion chamber of an internal combustion engine. The membrane assembly is accommodated in a housing of the pressure measuring device and has a resilient membrane. The membrane assembly additionally has at least one supporting member, against which an inner face of a pressurised region of the resilient membrane is at least partially supported.