3D Conductive Matrix PM Sensor for Uniform Soot Capture
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Solution Overview
Problem
Existing particulate matter (PM) sensors in exhaust gas flows suffer from low sensitivity and non-uniform soot deposition due to electrostatic forces, leading to inaccurate PM loading estimation and filtration efficiency diagnosis.
Innovation Solution
A particulate matter sensor design featuring two three-dimensional conductive matrices with extensions and passages forming soot capturing gaps, oriented orthogonally, to improve soot capture distribution and sensitivity, positioned downstream of a diesel particulate filter in an exhaust passage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If planar electrodes are used on a substrate surface, then the sensor structure is simple, but soot deposition is non-uniform and sensitivity is low
Solution Approach 1:
The patent transitions from planar 2D electrodes to three-dimensional matrices of conductive elements extending into the exhaust flow. This dimensional change creates multiple capturing surfaces and gaps that increase soot collection area and improve deposition uniformity throughout the sensor volume, directly resolving the contradiction between structural simplicity and measurement precision.
Solution Approach 2:
The conductive matrices are designed with porous structures containing multiple passages and gaps between conductive elements. This porosity allows exhaust gas to penetrate through the matrix while soot particles are captured on the conductive surfaces, significantly increasing the effective collection area and improving both sensitivity and uniformity without complicating the overall sensor structure.
2Reliability
If electrostatic forces are used for soot collection, then PM sensing is enabled, but only a small fraction of PM is collected leading to low sensitivity
Solution Approach 1:
The patent combines electrostatic charging of soot particles with physical interception on conductive matrix surfaces. The three-dimensional conductive elements create multiple electrostatic fields throughout the sensor volume, increasing the fraction of PM particles that experience electrostatic forces and are subsequently captured, thereby improving sensitivity while maintaining reliable PM sensing.
Solution Approach 2:
By extending conductive elements into the third dimension within the exhaust flow, the patent creates multiple electrostatic capturing zones throughout the sensor volume. This increases the probability that PM particles will encounter charged surfaces and be collected, directly improving sensor sensitivity beyond what planar electrodes can achieve.
3Ease of operation
If PM accumulates mostly at the inlet side, then flow distribution bias occurs, but soot loading becomes low and non-uniform
Solution Approach 1:
The three-dimensional conductive matrices are positioned and oriented to distribute soot capture throughout the sensor volume rather than concentrating it at the inlet. Elements extend in multiple directions to intercept soot particles regardless of their position in the flow, improving uniformity of soot loading across the entire sensor structure.
Solution Approach 2:
The porous structure with passages and gaps allows exhaust flow to penetrate through the conductive matrices, distributing soot capture throughout the internal volume of the sensor. This prevents flow distribution bias by ensuring that soot particles are captured throughout the sensor rather than only at the inlet surface, improving uniformity of soot loading.
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
Enhances the accuracy of PM loading estimation on filters, improves exhaust emissions compliance, reduces warranty costs, and extends exhaust component life by ensuring more uniform soot deposition and reliable sensor output.
Implementation Method 1
a first conductive matrix having a three dimensional shape defined by non-negligible dimensions in an x-dimension, a y-dimension, and a z-dimension to be charged to a first voltage to function as a positive electrode; and a second conductive matrix having a three dimensional shape defined by non-negligible dimensions in the x-dimension, the y-dimension, and the z-dimension to be charged to a second voltage to function as a negative electrode
Implementation Method 2
A change in voltage of the first and/or second matrix may be effected by soot forming in the soot capturing bridges
Data Source
AI summary
Methods and systems are provided for sensing particulate matter by a particulate matter (PM) sensor positioned upstream, or downstream, of a diesel particulate filter in an exhaust system. The PM sensor may include first and second conductive matrixes each having a three dimensional shape. The first matrix functions as a positive electrode, and the second functions as a negative electrode. Each matrix defines extensions and/or passages passing respectively through, and/or near, each other to form multiple soot capturing gaps. A first of the multiple soot capturing gaps is oriented orthogonal to a second of the multiple soot capturing gaps.