PM Sensor Uniform Accumulation via Partition Pore Gradient
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Solution Overview
Problem
Conventional PM sensors face reduced detection accuracy due to uneven PM accumulation in porous filters with non-uniform pore sizes and distributions, affecting capacitance measurements.
Innovation Solution
A PM sensor design featuring a porous member with a partition wall and electrodes, where a membrane layer with smaller average pore diameter is used on the upstream surface to accumulate PM, minimizing uneven accumulation and maintaining detection accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a porous filter with non-uniform pore sizes is used, then PM accumulation capacity is improved, but detection accuracy deteriorates due to uneven PM distribution
Solution Approach 1:
The partition wall is designed with non-uniform pore distribution where larger pores are concentrated in a specific region (the accumulation region). This local variation in pore quality allows PM to accumulate preferentially in that region, creating a localized high-concentration zone that improves detection accuracy while maintaining overall accumulation capacity.
2Reliability
If PM accumulates unevenly in the porous filter, then detection reliability is improved by creating a concentrated accumulation zone, but manufacturing precision requirements worsen
Solution Approach 1:
The invention changes the pore size parameter within the partition wall, creating a gradient or concentrated distribution of larger pores in the accumulation region. This parameter variation is designed to guide PM accumulation to a specific zone, improving detection reliability while the patent acknowledges this increases manufacturing complexity.
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 PM sensor effectively suppresses reductions in detection accuracy by ensuring uniform PM accumulation on the membrane layer, regardless of non-uniform pore sizes in the porous member, maintaining reliable capacitance measurements.
Implementation Method 1
a partition wall disposed in a passage of exhaust gas containing particulate matter; an accumulation section provided in a surface on a upstream side of the passage of the partition wall so that particulate matter accumulates on the surface
Implementation Method 2
The PM sensor derives the amount of PM accumulated in the porous filter according to the capacitance of a capacitor consisting of at least a pair of electrodes
Data Source
AI summary
This particulate matter (PM) sensor is provided with a porous body that has a partition disposed in a passage for exhaust gas including particulate matter, at least a pair of electrodes that oppose each other in a prescribed direction so as to sandwich the porous body, and a deposition part that includes the surface of the partition on the upstream side of the passage, has the particulate matter deposited thereon, and has, formed therein, pores having an average pore diameter smaller than the average pore diameter of the portion of the partition other than the deposition part.