Particulate Matter Sensor Particle Size Correction
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Solution Overview
Problem
Existing particulate matter detection devices struggle to accurately diagnose filter failures due to variations in particulate matter particle size, leading to inconsistent output values and incorrect diagnosis results.
Innovation Solution
A filter failure detection device that includes a sensor, particle size estimation section, and correction section, which estimates the average particle size of particulate matter and corrects sensor output or threshold values to account for particle size variations, ensuring accurate filter failure detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If particle size variations are not corrected, then the sensor can detect particulate matter amount, but the output value varies significantly due to particle size differences
Solution Approach 1:
The patent applies parameter changes by introducing a particle size correction coefficient that modifies the sensor output based on detected particle size. The control unit calculates a corrected particulate matter amount by multiplying the raw sensor output by this coefficient, thereby compensating for particle size variations and improving measurement consistency across different particle conditions.
Solution Approach 2:
The patent implements feedback by using the detected particle size information to adjust the particulate matter calculation. The system continuously monitors particle size and dynamically corrects the PM output based on real-time particle size conditions, creating a closed-loop correction mechanism that improves diagnosis reliability.
2Device complexity
If the sensor output is used directly for filter failure diagnosis, then the diagnosis process is simple, but incorrect diagnosis results occur due to particle size variations
Solution Approach 1:
The patent modifies the diagnosis process by introducing a correction parameter (particle size correction coefficient) that adjusts the sensor output before comparison with threshold values. This maintains the overall simplicity of the diagnosis workflow while improving accuracy through parameter adjustment rather than complex algorithmic changes.
Solution Approach 2:
The patent introduces a correction coefficient as an intermediary element between the raw sensor output and the final diagnosis decision. This intermediary adjusts the PM amount calculation based on particle size conditions, serving as a bridge that reconciles simple threshold comparison with accurate particle size compensation.
3Ease of operation
If threshold values are not corrected for particle size, then the comparison process remains straightforward, but diagnosis results vary with particle size changes
Solution Approach 1:
The patent applies parameter changes to the threshold values by adjusting them according to detected particle size. The control unit modifies the reference thresholds using particle size correction coefficients, ensuring that comparisons remain straightforward while maintaining accuracy across different particle size conditions.
Solution Approach 2:
The patent makes the threshold values dynamic rather than fixed. The thresholds are adjusted in real-time based on particle size detection, allowing the diagnosis system to adapt to varying particle conditions while maintaining the simplicity of threshold-based comparison methodology.
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 device effectively suppresses output value variations caused by particle size, leading to reliable filter failure diagnosis and reduced incorrect detection results.
Implementation Method 1
an electrical resistance type sensor which generates an output value corresponding to an amount of particulate matter contained in exhaust gas
Implementation Method 2
A heater for the particulate matter detection sensor is capable of heating the sensor element section to a particulate matter elimination temperature at which the particulate matter attached to the sensor element section is eliminated from the sensor element section
Data Source
Figure 1
Figure 2~3
Figure 4~5
AI summary
A control unit (6) estimates an output value of a PM sensor (S2) located at a downstream side of a DPF used as a reference filter, and detects whether the estimated output value exceeds a predetermined value (S3). When the estimated output value exceeds the predetermined value (YES in S3), the control unit detects an output value of the PM sensor (S4), and a heater heats the PM sensor (S5). The control unit detects an output value of the PM sensor (S6) after the PM sensor is heated, and calculates a change ratio of the output values of the PM sensor before and after heating (S7). The control unit estimates an average particle size of PM based on the calculated change ratio (S8), and detects whether the DPF has failed based on a comparison result of a corrected output value of the PM sensor with a threshold value.