Exhaust Gas Flow Area Ratio for PM Sensor Accuracy
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Solution Overview
Problem
Existing particulate matter concentration measuring apparatuses face accuracy degradation due to particulate matter accumulation on detection filters, leading to potential engine damage and decreased fuel economy, as they struggle to accurately measure concentrations and detect leaks beyond predetermined thresholds.
Innovation Solution
A particulate matter concentration measuring apparatus with a smaller cross-sectional exhaust gas collecting line, a particulate matter detection filter made of porous ceramic material, and a differential pressure sensor, which calculates soot load and concentration using specific formulas, and includes a configuration where the outlet side passage has a cross-sectional area equal to or larger than the inlet side, reducing measurement errors by minimizing external factor influence.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a particulate matter detection filter is used to measure PM concentration, then PM concentration can be detected, but measurement accuracy degrades due to PM accumulation on the filter
Solution Approach 1:
The patent changes the geometric parameters of the exhaust gas collecting line, specifically setting the outlet side cross-sectional area to be equal to or larger than the inlet side cross-sectional area. This parameter change optimizes flow distribution through the detection filter, reducing measurement errors caused by PM accumulation while maintaining accurate PM concentration detection.
2Quantity of substance
If PM is accumulated on the detection filter, then PM concentration measurement is enabled, but differential pressure detection accuracy is degraded
Solution Approach 1:
The patent optimizes the geometric parameters of the exhaust gas collecting line, specifically the cross-sectional areas at inlet and outlet sides of the detection filter. By setting the outlet area equal to or larger than the inlet area, the system maintains accurate differential pressure detection even when PM accumulates on the filter, thereby preserving measurement precision.
3Area of stationary object
If the exhaust gas collecting line has a smaller cross-sectional area, then the apparatus is more compact, but flow characteristics may be affected
Solution Approach 1:
The patent specifies that the outlet side cross-sectional area of the exhaust gas collecting line should be equal to or larger than the inlet side cross-sectional area. This parameter optimization allows the apparatus to maintain compact dimensions while preserving proper exhaust gas flow characteristics through the detection filter, avoiding flow distortion that would affect measurement accuracy.
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
This configuration allows for accurate detection of particulate matter accumulation and concentration measurement, reducing measurement errors and enabling timely regeneration of the Diesel Particulate Filter, thus preventing engine damage and maintaining fuel efficiency.
Implementation Method 1
a differential pressure sensor 22B measuring differential pressure between inlet and outlet of the particulate matter detection filter 22A
Implementation Method 2
a heater 22H is provided so as to burn and remove particulate matter (PM) when the particulate matter (PM) is accumulated on the particulate matter detection filter 22A to some extent
Implementation Method 3
a particulate matter detection filter 22A provided in the secondary exhaust line 21A
Data Source
AI summary
A particulate matter concentration measuring apparatus configured to measure concentration of particulate matter in exhaust gas passing through an exhaust line includes an exhaust gas collecting line branched from the exhaust line, a particulate matter detection filter provided in the exhaust gas collecting line, a differential pressure sensor configured to sense differential pressure between an inlet and an outlet of the particulate matter detection filter, a passage wall disposed so that the exhaust gas flows to a downstream side of the particulate matter detection filter, an inlet side passage through which the exhaust gas flows into the particulate matter detection filter in the passage wall, and an outlet side passage through which the exhaust gas flows out from the particulate matter detection filter. The outlet side passage has an outlet side cross-sectional area approximately 1.0 times or more larger than an inlet side cross-sectional area of the inlet side passage.