Particulate Matter Sensor With Variable Electrode Intervals
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Solution Overview
Problem
Conventional particulate matter detection sensors face challenges in sensitivity consistency, precision, and reliability due to narrow electrode intervals, which can lead to erroneous diagnoses and increased production costs, especially when dealing with coarse particles and misaligned gas flow.
Innovation Solution
A particulate matter detection sensor design featuring a pair of detection electrodes with alternating narrow and wide electrode intervals, where the narrow interval is centered and the wide interval is wider, enhancing sensitivity and reducing the impact of coarse particles while maintaining productivity and reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the electrode interval is narrowed to increase sensitivity, then the sensitivity of the sensor is improved, but the detection area becomes smaller and the sensor output becomes unstable when coarse particles are present
Solution Approach 1:
The patent applies local quality by creating different electrode intervals in different regions of the sensor. The center region has narrow electrode intervals to provide high sensitivity for detecting particulate matter, while the peripheral regions have wide electrode intervals to prevent instability caused by coarse particles. This spatial variation in electrode interval allows each region to perform its specific function optimally.
2Area of stationary object
If the number of detection electrodes is increased to enlarge the detection area, then the detection area is improved, but the production cost increases due to more laminate layers and electrode materials
Solution Approach 1:
The patent segments the sensor surface into multiple detection regions with different electrode interval characteristics. Instead of uniformly increasing the number of electrodes across the entire sensor, the invention divides the sensor into a center region and peripheral regions, each with optimized electrode configurations. This segmentation allows the detection area to be effectively enlarged through strategic placement of narrow-interval electrodes in the center while using wide-interval electrodes in peripheral areas, thereby maintaining cost-effectiveness.
3Measurement precision
If the electrode interval is narrowed to improve sensitivity, then the sensitivity is improved, but the difference in sensitivity between sensors increases due to dimensional precision and assembly precision variations
Solution Approach 1:
The patent changes the parameter of electrode interval from a uniform value to a spatially varying value with multiple discrete intervals. By introducing wide electrode intervals in peripheral regions alongside narrow intervals in the center, the invention creates a more robust sensor design that is less sensitive to manufacturing tolerances. The wide intervals in peripheral regions compensate for variations caused by assembly precision issues, thereby reducing the difference in sensitivity between individual sensors.
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 achieves improved sensitivity and detection precision with reduced variability in sensor output due to coarse particles, while maintaining cost-effectiveness and assembly precision, thus enhancing the accuracy of particulate matter detection.
Implementation Method 1
Once an electrostatic field is formed by application of a voltage, charged particulate matter is attracted and this particulate matter accumulates between electrodes
Implementation Method 2
charged particulate matter is attracted and this particulate matter accumulates between electrodes
Implementation Method 3
An amount of particulate matter contained in the exhaust gas may be thus detected from a change in a resistance value between the electrodes
Data Source
AI summary
A sensor element which has a pair of positive and negative detection electrodes disposed on a surface of an insulation body as a detecting portion and a cover body configured to cover an opening of a cylindrical housing. The cover body is provided with gas inlet and outlet holes via which the measuring gas is introduced and discharged. The pair of detection electrodes have a plurality of wire electrodes. The wire electrodes electrically connected to the positive electrode and the wire electrodes electrically connected to the negative electrode are alternately arranged in parallel. Any one of a first insulation layer which is a narrow electrode interval Dn and a second insulation layer which is a wide electrode interval Dw, arranged between adjacent wire electrodes, and the first insulation layer arranged in a center part of the detecting portion.