Laminated Gas Sensor Porous Protection Layer Crack Prevention
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Solution Overview
Problem
Conventional laminated gas sensors with porous protection layers fail to adequately prevent cracks caused by water or oil droplets adhering to the sensor elements during thermal shock, leading to potential damage and reduced accuracy in gas detection.
Innovation Solution
A laminated gas sensor element with a porous protection layer having a specific distribution and size of small and large pores, along with a controlled porosity and thickness, is designed to absorb thermal stress and prevent water adhesion, featuring a surface with 10 or more small pores (1 μm to 5 μm in diameter) and one to less than 20 large pores (8 μm to 20 μm in diameter within defined areas, and a porosity of 15% to 65%.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a porous protection layer is formed on the gas sensor element to prevent water adhesion, then resistance to water adhesion is improved, but the protection layer may still fail to prevent crack generation under thermal shock
Solution Approach 1:
The patent applies porous materials by forming a protection layer with controlled porosity (10-50%) containing pores of specific size distribution (1-20 μm). The porous structure allows the layer to absorb thermal stress while maintaining water adhesion resistance, preventing crack generation under thermal shock conditions.
Solution Approach 2:
The patent changes physical parameters of the protection layer including porosity (10-50%), pore size distribution (1-20 μm), and thickness (50-500 μm). These parameter optimizations enable the layer to simultaneously achieve water adhesion resistance and crack prevention by controlling how the layer responds to thermal stress and water contact.
2Strength
If the protection layer thickness is increased to improve crack resistance, then strength is improved, but gas detection efficiency may deteriorate
Solution Approach 1:
The patent optimizes the thickness parameter of the protection layer within the range of 50-500 μm. This controlled thickness provides sufficient mechanical strength and crack resistance while maintaining adequate gas permeability for efficient gas detection, balancing both requirements through precise parameter control.
3Reliability
If the protection layer porosity is increased to improve thermal shock resistance, then reliability is improved, but water penetration resistance may deteriorate
Solution Approach 1:
The patent uses porous materials with controlled porosity (10-50%) and specific pore size distribution (1-20 μm). The porous structure provides thermal shock resistance through stress absorption while the controlled pore size and distribution prevent water penetration by creating a tortuous path that blocks water droplets.
Solution Approach 2:
The protection layer is formed as a composite structure with specific porosity and pore size distribution, combining the benefits of thermal shock resistance through porosity with water penetration resistance through controlled pore architecture, achieving both functions simultaneously.
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 designed porous protection layer effectively restrains crack generation in the gas sensor element, maintaining accuracy and preventing water penetration while allowing gas detection, with optimal porosity and thickness balancing protection and detection efficiency.
Implementation Method 1
the generation of a crack can be restrained... upon adhesion of water to the gas sensor element... thermal shock
Implementation Method 2
adhesion, to the gas sensor element, of a water or oil droplet contained in a gas to be measured... adhesion of water
Data Source
AI summary
A laminated gas sensor element including a detection element including a solid electrolyte body having a pair of electrodes formed thereon laminated together with a heater element. A porous protection layer is formed on at least a distal end portion of the laminated gas sensor element which is to be exposed to a gas to be measured. The surface of the porous protection layer has 10 or more small pores each having a diameter of 1 μm to 5 μm inclusive and an aspect ratio of 0.5 to 2.0 inclusive within an area measuring 50 μm×50 μm, and one to less than 20 large pores each having a diameter of 8 μm to 20 μm inclusive and an aspect ratio of 0.5 to 2.0 inclusive within an area measuring 100 μm×100 μm. Also disclosed is a method for manufacturing the laminated gas sensor.