Exhaust Temperature Sensor Diagnosis via Flow Normalization
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Diagnosing the operation of multiple temperature sensors in an exhaust gas aftertreatment system is challenging due to their operation within different temperature zones or ranges, making direct comparison impractical.
Innovation Solution
A method and system that determine average temperature differentials between temperature sensors positioned along a single exhaust flow path, using exhaust gas flow rate to calculate these differentials and generate fault signals if differences exceed a threshold, allowing for diagnostic pass or fail signals and isolation of failed sensors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If temperature sensors are positioned at different locations along the exhaust flow path to monitor various zones, then the diagnostic coverage is improved, but direct comparison of temperature signals becomes impractical due to different temperature zones
Solution Approach 1:
The patent introduces exhaust gas flow rate as an intermediary parameter to normalize temperature comparisons. By using flow rate data, the system can account for the thermal mass and heat capacity variations across different sensor locations, enabling meaningful comparison of temperature signals despite sensors operating in different temperature zones. This mediator allows the diagnostic system to function effectively across the entire exhaust system.
2Reliability
If multiple temperature sensors are used to cover different exhaust zones, then the diagnostic capability is improved, but the system complexity increases
Solution Approach 1:
The patent creates a universal diagnostic approach that can be applied to any number of temperature sensors positioned at any locations along the exhaust flow path. The methodology uses a standardized procedure involving flow rate normalization and differential temperature calculation that works regardless of the specific sensor configuration, making the system scalable and adaptable to different engine and exhaust system designs.
3Reliability
If temperature sensors are placed far apart to monitor different exhaust aftertreatment components, then the diagnostic coverage is improved, but the temperature differentials become harder to interpret
Solution Approach 1:
The patent transforms the temperature measurement parameter by introducing flow rate normalization. Instead of directly comparing absolute temperature values or simple temperature differentials, the system calculates differentials normalized by exhaust gas flow rate. This parameter transformation allows for precise interpretation of temperature variations even over large spatial distances, as the flow rate accounts for the thermal energy transport between sensor locations.
Data Source
AI summary
A system and method are provided for diagnosing temperature sensor operation in an exhaust aftertreatment system. Temperature signals from first, second and third temperature sensors and a flow signal are received by a control circuit. The three temperature sensors are positioned in fluid communication with an exhaust flow path fluidly coupled to an exhaust manifold of an internal combustion engine, and the flow signal represents the flow rate of exhaust gas through the exhaust flow path. The control circuit determines average temperature differentials between each of the first, second and third temperature sensors as functions of the flow signal and corresponding ones of the first, second and third temperature signals, and produces a diagnostic fail signal if any of the differences between the average temperature differentials exceed a threshold value.