Image Charge Sensor for Exhaust Particulate Diagnostics
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Solution Overview
Problem
Current particulate matter filters in automotive emission systems suffer from irreversible efficiency losses due to temperature excursions during regeneration, leading to increased emissions above regulated limits, and existing diagnostic tools are impractical for on-board use due to cost and calibration requirements.
Innovation Solution
An apparatus comprising an internal combustion engine, an exhaust system with particulate sensors, and a controller that determines changes in exhaust flow rates to assess sensor degradation, using image charge sensors that can detect particulate matter dislodged from the exhaust system walls during sudden flow increases, allowing for effective monitoring of particulate filter performance without requiring precise calibration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If laboratory grade optical measurement instruments are used for particulate matter measurements, then measurement precision is improved, but device complexity and cost increase, making them impractical for on-board use
Solution Approach 1:
The patent replaces expensive, complex laboratory-grade optical measurement instruments with simpler, more robust image charge sensors that are suitable for on-board use. The image charge sensor uses a charged rod or plate to detect particulate matter through electrical field interactions, eliminating the need for complex optical systems while maintaining adequate measurement capability for diagnostic purposes.
Solution Approach 2:
The patent substitutes optical measurement systems with an electrical field-based detection system. The image charge sensor utilizes electrical fields to detect particulate matter, replacing the mechanical and optical components of laboratory instruments with a simpler electrical measurement approach that is more suitable for automotive applications.
2Measurement precision
If laboratory grade optical measurement instruments are used for particulate matter measurements, then measurement precision is improved, but ease of operation deteriorates due to extensive calibration requirements
Solution Approach 1:
The image charge sensor performs self-diagnosis by monitoring its own output signal characteristics. The system detects sensor degradation by analyzing changes in the sensor's response to known exhaust flow conditions, eliminating the need for external calibration procedures. The sensor essentially calibrates itself through operational feedback, making the system easier to operate while maintaining measurement accuracy.
3Measurement precision
If optical measurement instruments are used, then measurement precision is improved, but loss of time increases due to periodic cleaning requirements
Solution Approach 1:
The patent employs a simpler image charge sensor that is less susceptible to contamination and does not require periodic cleaning like optical instruments. The electrical field-based detection method is more robust to environmental conditions and particulate accumulation, eliminating the time loss associated with maintaining optical systems while preserving adequate measurement precision for diagnostic applications.
4Productivity
If particulate filter trapping efficiency decreases due to temperature excursions, then reliability deteriorates, but productivity is improved as the filter allows more exhaust flow
Solution Approach 1:
The patent implements a diagnostic system that continuously monitors the particulate filter's trapping efficiency using the image charge sensor. By comparing sensor readings under controlled exhaust flow conditions, the system provides feedback on filter performance and can detect degradation caused by temperature excursions. This feedback mechanism allows the vehicle operator to understand the actual filter status despite increased exhaust flow, maintaining awareness of reliability issues.
Solution Approach 2:
The patent accepts that the filter may operate with reduced trapping efficiency under certain conditions (allowing excessive exhaust flow through cracks) but uses the diagnostic system to detect and report these partial failures. The system doesn't prevent the physical degradation but provides partial monitoring capability to alert operators when trapping efficiency falls below acceptable levels despite increased flow throughput.
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 solution enables efficient monitoring of particulate filter performance, distinguishing between properly functioning and degraded filters, and activates a malfunction indicator light when thresholds are exceeded, using less expensive and robust image charge sensors suitable for on-board use.
Implementation Method 1
The sensor typically includes a charged rod or plate and a means of measuring an image charge developed on the rod or plate by particulate matter passing near the rod or plate
Data Source
AI summary
An apparatus comprising an internal combustion engine, an exhaust system in communication with the engine, a particulate sensor associated with the exhaust system, and a controller in electrical communication with the particulate sensor, wherein the controller is configured to determine a change in a rate of exhaust flow in the exhaust system, to compare the change in the rate of exhaust flow to a preselected threshold rate of change; and if the change in the rate of exhaust flow has a preselected relationship to the preselected threshold rate of change, then to determine a degradation of the sensor.