Exhaust Purifier Removal Detection Using Thermal Sensors
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Solution Overview
Problem
Existing diagnostic systems for exhaust gas purification devices in engines are unable to accurately determine if the device has been removed from the exhaust pipe, leading to potential errors in failure diagnosis.
Innovation Solution
A removal determination device that uses input and output temperature sensors and a controller to assess the presence of an exhaust gas purification device in the exhaust pipe by analyzing temperature differences and integrated exhaust gas amounts, particularly after a predetermined engine stop time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If temperature sensors are used to diagnose switching valve failure, then the diagnosis can be performed, but erroneous determination occurs when engine is restarted after short idle time due to residual thermal energy
Solution Approach 1:
The system performs preliminary detection of the purification device's thermal state by measuring temperatures at multiple positions (upstream, downstream, and internal surfaces of the casing) before making the final determination. This preliminary thermal state assessment prevents erroneous diagnoses by identifying when residual heat from previous operation is still present.
Solution Approach 2:
The patent introduces an intermediary thermal state detection mechanism that measures temperatures at multiple positions within the casing to assess the purification device's thermal state. This intermediary measurement layer separates the raw temperature data from the final diagnostic conclusion, allowing for more accurate determination by filtering out false signals from residual heat.
2Measurement precision
If temperature difference between upstream and downstream sensors is used to determine purification device presence, then removal can be detected, but thermal energy remaining in the engine or purification device causes erroneous determinations
Solution Approach 1:
The patent segments the temperature measurement into multiple distinct positions: upstream temperature, downstream temperature, and internal surface temperatures at multiple locations within the casing. This segmentation allows the system to independently assess the thermal state of different components and distinguish between actual purification device presence and false signals from residual heat.
Solution Approach 2:
The patent introduces an intermediary thermal state detection mechanism that measures temperatures at multiple positions (upstream, downstream, and internal surfaces of the casing) before making the final determination. This preliminary thermal state assessment prevents erroneous diagnoses by identifying when residual heat from previous operation is still present.
3Difficulty of detecting and measuring
If the exhaust gas purification device is removed from the exhaust pipe, then theft or damage occurs, but existing diagnostic systems cannot accurately determine removal due to unchanged exhaust gas flow direction
Solution Approach 1:
The patent replaces mechanical flow direction detection with thermal field-based detection. Instead of trying to detect changes in exhaust gas flow direction (which remains unchanged regardless of purification device presence), the system uses temperature field measurements at multiple positions to infer the presence or absence of the purification device through thermal energy analysis.
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 determines the presence or absence of the exhaust gas purification device, reducing erroneous determinations caused by thermal energy remaining in the engine or purification device, and ensuring accurate diagnosis.
Implementation Method 1
an input temperature sensor that detects a temperature at an upstream side of the casing; an output temperature sensor that detects a temperature at a downstream side of the casing
Data Source
AI summary
A removal determination device that accurately determines a removal of an exhaust gas purification device from an exhaust pipe. The removal determination device comprises: an input temperature sensor detecting a temperature at an upstream side of casing; an output temperature sensor detecting a temperature at a downstream side of the casing; an engine stop time collector measuring a time period from an inactivation of an engine to a startup of the engine; and a determiner determining a presence of the exhaust gas purifying device based on the input temperature and the output temperature, in a case that the time period is equal to or longer than a predetermined time.