Sensor Device Non-Coplanar Lid Sealing
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Solution Overview
Problem
Existing force sensors with piezoelectric materials face challenges in maintaining air-tight sealing over long periods due to dimensional errors and moisture infiltration, leading to unstable measurements, especially in poor environmental conditions.
Innovation Solution
A sensor device design featuring a first member with a recess and a second member that seals the recess, where the contacting surface and joint surface are not the same flat surface, allowing for stress distribution and preventing concentration at the joint, thereby ensuring stable air-tight sealing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the contacting surface and joint surface are the same flat surface, then the structure is simple, but stress concentrates at the joint causing sealing failure
Solution Approach 1:
The lid is divided into two distinct surfaces: a contacting surface for joining with the sensor element and a joint surface for joining with the package. This segmentation allows each surface to be optimized for its specific function, preventing stress concentration at the joint while maintaining structural simplicity.
Solution Approach 2:
Different regions of the lid are given different properties: the contacting surface is designed to match the sensor element's geometry for precise joining, while the joint surface is designed to match the package's opening for robust sealing. This local differentiation ensures stress is distributed appropriately without complicating the overall structure.
2Strength
If welding is used to attach the lid to the package, then strong joining is achieved, but gaps may form due to dimensional errors
Solution Approach 1:
The lid is pre-formed with a joint surface that has precise dimensions and geometry matching the package opening. This preliminary preparation ensures that when welding is performed, minimal gaps are created despite inherent dimensional variations in the components, maintaining both joining strength and manufacturing precision.
3Stability of the object's composition
If the lid is rigidly joined to the package, then structural stability is improved, but stress concentration causes breakage over time
Solution Approach 1:
By separating the contacting surface and joint surface, the lid can maintain rigid structural stability for immediate performance while the segmented design allows stress distribution that prevents fatigue failure over time, extending the sealing duration.
Solution Approach 2:
The segmented lid design provides a degree of flexibility in stress distribution while maintaining overall structural stability. The separation of surfaces allows the structure to dynamically respond to applied forces, reducing stress concentration points that would otherwise lead to breakage and sealing failure over time.
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 design effectively prevents stress concentration at the joint, ensuring long-term air-tight sealing and stable measurement performance even in harsh environments.
Implementation Method 1
The crystal plates 216 output (induce) an electric charge accompanied with the applied force to the sensing electrode 218 by a piezoelectric effect
Data Source
AI summary
A sensor device includes a package, a sensor element that is disposed in the package, and a lid that seals the package, in which the sensor element includes a contacting surface that comes in contact with the lid, the package includes a joint surface which is joined to the lid, and the contacting surface and the joint surface are not on the same flat surface.