Particulate Matter Sensor Calibration for Diesel Exhaust
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Solution Overview
Problem
Increased soot loading in diesel particulate filters (DPFs) leads to increased exhaust flow resistance and potential damage, necessitating effective regeneration methods to maintain engine performance and comply with regulatory emissions standards.
Innovation Solution
A system comprising a calibrated PM sensor, processor, and regenerating unit that monitors and controls the DPF's operational modes, using temperature and fuel injection to oxidize soot, and automatically calibrates the sensor to ensure accurate particulate matter measurements and regeneration timing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If the DPF accumulates soot during normal operation, then particulate matter is trapped and emissions are reduced, but exhaust flow resistance increases and engine performance deteriorates
Solution Approach 1:
The system implements periodic regeneration cycles where the DPF is actively cleaned by injecting fuel to create high-temperature combustion that burns off accumulated soot. This periodic action resets the filter's flow resistance while maintaining continuous particulate trapping during normal operation.
Solution Approach 2:
The system converts the harmful accumulated soot into a beneficial fuel source by injecting additional fuel that reacts with the trapped particulate matter. This combustion process generates high temperatures that not only clean the filter but also produce useful thermal energy.
2Productivity
If passive regeneration is used during high load operation, then PM oxidation temperature is achieved and soot is removed, but engine operation is limited to high load conditions
Solution Approach 1:
The active regeneration system can operate across the entire engine load range, not just during high load conditions. The fuel injection system can deliver the required fuel regardless of engine operating conditions, making the regeneration capability universal and adaptable to any operational scenario.
Solution Approach 2:
The system changes the operational parameters by injecting fuel directly into the exhaust stream, creating localized high-temperature zones that enable soot oxidation at temperatures and conditions different from normal passive regeneration. This allows regeneration to occur under varied engine operating conditions.
3Device complexity
If the PM sensor is not calibrated, then the system structure is simpler, but accurate measurement of particulate matter and proper regeneration timing cannot be ensured
Solution Approach 1:
The PM sensor performs self-calibration by using its own measurement data. The sensor compares particulate matter readings taken before and after regeneration events, automatically adjusting its baseline to account for drift. This self-service calibration eliminates the need for external calibration equipment or manual intervention.
Solution Approach 2:
The system implements feedback-based calibration where the PM sensor continuously monitors particulate matter levels and uses this information to adjust its calibration parameters. The calibration process uses feedback from actual regeneration events and measured particulate concentrations to maintain measurement accuracy over time.
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 system effectively manages DPF regeneration, maintaining engine performance, adhering to emissions regulations, and enabling continuous monitoring and calibration of PM sensors for optimal filtration efficiency and early detection of filter failures.
Implementation Method 1
a PM oxidation temperature is achieved during normal engine operation (high load leading to engine exhaust above the light-off temperature)
Data Source
AI summary
A system includes a filter, a sensor, a processor, and a memory. The filter can be coupled to an engine exhaust and can operate in an accumulating mode during which particulate matter (PM) from the engine is trapped and also operate in a regenerating mode during which PM in the filter is emitted. The sensor is coupled to a discharge port of the filter and has an output to provide a sensor signal based on a concentration of PM in the filtered exhaust. The processor is coupled to receive the sensor signal and operable to determine at least one of a base level for the sensor signal during the accumulating mode and a regenerate level for the sensor signal during the regenerating mode, and operable to determine a calibration value for the sensor using at least one of the base level and the regenerate level. The memory stores the calibration value.