Sensor Board with Segmented Electrodes for PM Detection
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Solution Overview
Problem
Current PM detection sensors for DPF systems in vehicles lack sensitivity and efficiency in detecting particulate matter in exhaust gases, requiring improvements in electrode design and substrate materials to enhance detection accuracy and durability.
Innovation Solution
A sensor board with a multilayer structure featuring closely spaced cylindrical sensing electrodes and a heat-generating electrode on a ceramic sintered substrate, utilizing a manganese-containing glass phase for fracture resistance and improved wettability, and oxidation-resistant metal materials to maintain sensitivity and durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the gap between sensing electrodes is narrowed to improve detection sensitivity, then measurement precision is improved, but device complexity increases due to manufacturing difficulties
Solution Approach 1:
The sensing electrodes are divided into multiple segments along the exhaust gas flow direction, with each segment independently detecting PM concentration. This segmentation allows the use of larger electrode gaps while maintaining overall detection sensitivity through combined signal processing of multiple segments.
Solution Approach 2:
The patent transitions from a single-point detection approach to a multi-segment distributed detection approach along the flow direction. This dimensional expansion allows each electrode to have sufficient gap distance for manufacturing while the collective arrangement maintains high detection sensitivity through spatial distribution.
2Ease of manufacture
If conventional electrode materials are used to simplify manufacturing, then ease of manufacture is improved, but reliability decreases due to oxidation and sensitivity loss
Solution Approach 1:
The sensing electrodes use a composite material structure combining a metal substrate (e.g., stainless steel) with a ceramic coating layer (e.g., platinum or other oxidation-resistant ceramic). This composite structure provides both mechanical strength for manufacturing and oxidation resistance for reliability in high-temperature exhaust environments.
Solution Approach 2:
The patent changes the material parameters of the electrodes by selecting materials with specific properties: high melting point, low oxidation rate, and appropriate electrical conductivity. These parameter changes ensure the electrodes maintain sensitivity and structural integrity under exhaust gas conditions without complicating the manufacturing process.
3Productivity
If standard substrate materials are used to reduce cost, then productivity is improved, but durability decreases due to thermal shock and fracture
Solution Approach 1:
The substrate uses a composite ceramic material system incorporating manganese-containing glass phase combined with crystalline phases (e.g., mullite, cordierite, or alumina). This composite structure provides high thermal shock resistance and mechanical strength while maintaining compatibility with standard manufacturing processes for ceramic substrates.
Solution Approach 2:
The substrate employs a porous ceramic structure with controlled porosity that enhances thermal shock resistance by reducing thermal stress through the porous network. This porous structure also maintains manufacturing efficiency using established ceramic sintering techniques while significantly improving durability against thermal cycling in exhaust systems.
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 sensor board achieves enhanced sensitivity and durability by narrowing the gap between sensing electrodes and using a manganese-containing glass phase for thermal shock resistance, enabling effective detection of particulate matter and long-duration continuous measurement.
Implementation Method 1
utilizing a manganese-containing glass phase for fracture resistance and improved wettability, and oxidation-resistant metal materials to maintain sensitivity and durability
Implementation Method 2
This device detects particulate matter on the basis of variation in electrical characteristics resulting from accumulation of detection targets, such as PM contained in exhaust gas, between a pair of sensing electrodes
Implementation Method 3
A sensor board with a multilayer structure featuring closely spaced cylindrical sensing electrodes and a heat-generating electrode on a ceramic sintered substrate
Data Source
Figure 1A~1E
Figure 2
Figure 3
AI summary
A sensor board according to the present disclosure includes an insulating substrate; a pair of a positive sensing electrode and a negative sensing electrode which is located in the insulating substrate, the pair of sensing electrodes including at least a pair of a positive columnar electrode and a negative columnar electrode, each of the pair of columnar electrodes including a part exposed at a first face of the insulating substrate; and innerlayer wiring lines that are embedded within the insulating substrate and correspond to each of the pair of sensing electrodes, respectively.