Multi-layer Diaphragm Pressure Sensor for Hysteresis Reduction
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Solution Overview
Problem
Pressure sensors for sanitary usage face challenges in achieving high pressure resistance performance while minimizing measurement error and maximizing sensitivity, as the demands for diaphragm rigidity are contradictory, requiring a balance between high strength and low rigidity to suppress hysteresis and enhance sensitivity.
Innovation Solution
A pressure sensor with a multi-layer diaphragm structure comprising thin plate members that are independently deformable and in press-contact, supported by a housing, allowing for a distributed pressure response that reduces stress and enhances sensitivity, achieved through a combination of materials with different properties and structural features like convex portions and lubrication members.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a high-strength and high-rigidity diaphragm with larger film thickness is adopted, then pressure capacity is improved and measurement error is reduced, but sensor sensitivity deteriorates
Solution Approach 1:
The diaphragm is divided into multiple thin plate members (first thin plate member, second thin plate member, third thin plate member) stacked in layers. Each layer has a thickness of 5-20 μm, and they are arranged to distribute the pressure load, reducing stress concentration while maintaining overall structural strength and enabling significant deformation for high sensitivity detection
Solution Approach 2:
The patent uses composite structure of multiple thin plate members with different material properties. The first thin plate member contacts the measurement target fluid, while subsequent layers provide structural support. This composite approach allows optimization of each layer's properties to balance strength and sensitivity requirements
2Measurement precision
If a low-rigidity diaphragm is adopted, then sensor sensitivity is improved, but measurement error increases due to hysteresis
Solution Approach 1:
The diaphragm is segmented into multiple thin layers that deform independently under pressure. This segmentation allows each layer to contribute to the overall deformation without excessive hysteresis, as the thin plate structure reduces internal stress accumulation compared to a single thick diaphragm
Solution Approach 2:
The patent changes the thickness parameter of individual plate members to 5-20 μm, which is thin enough to allow significant deformation for high sensitivity but maintains dimensional stability to reduce hysteresis effects. The multi-layer configuration compensates for the thinness by distributing mechanical loads
3Device complexity
If the diaphragm structure is simplified, then device complexity is reduced, but manufacturing precision requirements increase
Solution Approach 1:
The diaphragm is segmented into multiple thin plate members that are stacked and joined together. This segmentation, while structurally complex, uses standardized thin plate components that can be manufactured with consistent dimensions, actually reducing the precision requirements compared to manufacturing a single complex-shaped diaphragm
Solution Approach 2:
Multiple thin plate members are joined together to form the complete diaphragm structure. The joining process integrates the individual layers into a unified component that functions as a single element, simplifying the overall device assembly while maintaining the benefits of the multi-layer structure
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 multi-layer diaphragm structure effectively improves pressure resistance performance, reduces measurement error, and enhances sensitivity by distributing pressure forces and reducing stress concentrations, thereby achieving a balance between contradictory requirements.
Implementation Method 1
the plurality of thin plate members are deformed independently of each other while at least part of the plurality of thin plate members is in press-contact to each other in a pressure receiving state
Implementation Method 2
a convex portion (11c, 12c) may be provided on at least one of front and back surfaces of at least part of the plurality of thin plate members
Implementation Method 3
a lubrication member (40, 50) may be provided between two adjacent plate members of the plurality of thin plate members
Data Source
AI summary
To provide a pressure sensor that has high pressure resistance performance, small measurement error by suppressing hysteresis with respect to pressure, and high sensitivity and high productivity, a pressure sensor includes a diaphragm unit with a first main surface that receives a measurement target fluid's pressure and a second main surface located on the opposite side of this first main surface, a housing, and a sensing unit that outputs the diaphragm unit's deformation as an electric signal, in which at least part of the diaphragm unit has a multi-layer structure in which a plurality of thin plate members are stacked, and the plurality of thin plate members are deformed independently of each other while at least part of the plurality of thin plate members is in press-contact to each other in a pressure receiving state in which the measurement target fluid's pressure is applied to the first main surface.