Exhaust Oxygen Sensor Correlation for Particulate Filter Leakage Detection
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Solution Overview
Problem
Existing methods for detecting particulate filter leakage in internal combustion engines, such as those using pressure sensors, are costly, require frequent sensor replacement, and add complexity, while methods involving particulate and temperature sensors require frequent regeneration and limited ongoing monitoring opportunities.
Innovation Solution
Correlating the output of upstream and downstream exhaust oxygen sensors with the pressure drop across a particulate filter during specific conditions, where oxygen concentration remains constant, to infer filter soot levels and detect leakage, thereby utilizing existing sensors to estimate filter health without additional dedicated sensors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If pressure sensors are added to detect particulate filter leakage, then detection capability is improved, but system cost and complexity increase
Solution Approach 1:
The patent makes existing exhaust oxygen sensors perform a dual function: their primary function of measuring oxygen concentration is maintained, and they are additionally used to detect pressure drop across the particulate filter by comparing readings during constant oxygen concentration conditions. This eliminates the need for dedicated pressure sensors while maintaining leak detection capability
Solution Approach 2:
The existing exhaust oxygen sensors monitor their own environment and use their existing measurements to detect filter health. The sensors serve themselves by providing data that can be interpreted for both oxygen concentration and pressure drop detection, eliminating the need for separate monitoring systems
2Measurement precision
If pressure sensors are installed in the exhaust system, then filter health monitoring is improved, but sensor durability and reliability worsen due to harsh exhaust conditions
Solution Approach 1:
The patent utilizes existing oxygen sensors that are already designed to withstand exhaust conditions for their original purpose, and leverages their data for additional pressure drop detection. This avoids introducing new sensors that would be exposed to harsh conditions and require replacement
3Measurement precision
If multiple sensors (pressure, temperature, particulate) are used for filter diagnostics, then detection accuracy is improved, but component cost and control complexity increase
Solution Approach 1:
The patent makes existing oxygen sensors multi-functional by using them for both their primary oxygen measurement function and for pressure drop detection across the filter. This eliminates the need for additional temperature sensors, particulate sensors, or pressure sensors, reducing overall system complexity while maintaining diagnostic accuracy
Solution Approach 2:
The patent combines the function of oxygen concentration measurement and pressure drop detection into a single measurement system using existing oxygen sensors. By correlating oxygen sensor readings with flow rate data, the system merges multiple diagnostic functions into one integrated approach
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 allows for effective particulate filter leakage detection using existing exhaust gas sensors, reducing component costs and maintaining diagnostic routine reliability, thereby improving emissions compliance.
Implementation Method 1
since the exhaust gas sensors measure a partial pressure of exhaust oxygen
Implementation Method 2
correlating an output of an upstream exhaust oxygen sensor and a downstream exhaust oxygen sensor with a pressure drop across an exhaust particulate filter
Data Source
AI summary
A method and system is provided for correlating a pressure drop across an exhaust particulate filter with the output of an upstream exhaust oxygen sensor and a downstream exhaust oxygen sensor. The pressure drop is then used to infer leakage of the filter during conditions when an exhaust oxygen concentration across the filter is substantially constant. The diagnostic may be performed during selected entry conditions such as when a particulate level in the GPF is below a predetermined threshold, exhaust flow rate is above a threshold rate, and an absolute exhaust flow rate derivative is below a threshold derivative.