Diesel Particulate Filter Control via CO2 Signature Monitoring
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Solution Overview
Problem
Existing particulate matter (PM) sensors in diesel engines struggle to accurately differentiate between a degraded diesel particulate filter (DPF) and a degraded regeneration operation, due to their resistive sensing mechanisms and indirect correlation with CO2 levels, leading to reduced sensitivity and inability to identify filter degradation effectively.
Innovation Solution
Employing a CO2 sensor positioned downstream of the DPF to estimate the CO2 signature of oxidized post-filter exhaust PMs during regeneration, allowing for direct correlation with soot levels and enabling real-time monitoring and adjustment of regeneration conditions to address filter and regeneration degradation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If resistive sensing-based PM sensors are used to detect particulate matter, then the sensor can detect the presence of PMs electrically, but the sensor has a dead-band during which PMs must accumulate before the sensor responds, reducing sensitivity to degraded DPF
Solution Approach 1:
The patent replaces resistive sensing-based PM sensors with laser-based scattering sensors that detect particulate matter through light scattering principles. This substitution eliminates the dead-band issue inherent in resistive sensors, as laser scattering sensors can detect PMs immediately upon presence without requiring accumulation, thereby improving measurement precision and response time simultaneously
2Measurement precision
If CO2 sensors are used to indirectly infer soot load on the filter, then the system can monitor exhaust CO2 levels, but the indirect correlation between filter soot levels and exhaust CO2 levels reduces accuracy in determining soot load
Solution Approach 1:
The patent replaces indirect CO2-based soot load inference with direct laser scattering-based PM detection. The laser sensor directly measures particulate matter concentration in the exhaust stream, providing accurate soot load determination without relying on indirect correlations with CO2 levels, thereby eliminating information loss and improving measurement precision
3Measurement precision
If small differences in resistance are used by PM sensors to detect PM levels, then the sensor can operate with simple electrical circuits, but the small resistance differences reduce the ability to distinguish between degraded DPF and marginal DPF
Solution Approach 1:
The patent replaces simple electrical resistance-based sensing with laser-based optical scattering sensing. The laser sensor measures light scattering intensity, which provides large, easily distinguishable signals that clearly differentiate between degraded and marginal DPF conditions. This substitution maintains device simplicity while dramatically improving measurement precision and diagnostic capability
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 approach enhances the sensitivity and resolution of filter diagnostics, improving the ability to identify degraded filters and regeneration operations, thereby enhancing emissions control and reducing the risk of PM slip into exhaust emissions.
Implementation Method 1
The CO2 generated during regeneration, from oxidation of exhaust soot on the substrate, may be estimated by the downstream CO2 sensor
Implementation Method 2
oxidize post-filter exhaust particulate matters (that is, exhaust soot) on the heated substrate using oxygen present in the exhaust gas
Data Source
AI summary
Methods and systems are provided for managing particulate emissions in an engine including a particulate filter and a CO2 sensor downstream of the filter. A CO2 sensor may be used to infer the presence of particulate matter in the exhaust, downstream of the filter. By sensing particulate matter in the post-filter exhaust, filter degradation may be identified.