Exhaust Sensor Activation Control via Elimination Time Function
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Solution Overview
Problem
Conventional methods for activating fluid-sensitive sensors in exhaust treatment systems are imprecise, leading to potential sensor damage from liquid fluid presence, and are complex, requiring extensive calibration for various engines and systems.
Innovation Solution
A method determining the absence of liquid fluid in the exhaust stream using an elimination time function based on exhaust temperature and mass flow, ensuring sensors are activated only when the stream is free of liquid, thereby minimizing risk and simplifying implementation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional activation methods are used, then sensors may be activated early, but sensor damage risk increases due to liquid fluid presence
Solution Approach 1:
The system performs preliminary determination of liquid fluid presence using temperature and mass flow measurements before activating the sensor. The elimination time function calculates whether the exhaust stream is free of liquid fluid at the sensor location, ensuring sensors are only activated when safe, thus resolving the contradiction between early activation and damage risk
Solution Approach 2:
The patent replaces complex mechanical calibration systems with a mathematical elimination time function based on temperature and mass flow measurements. This substitution simplifies the determination process while accurately predicting liquid fluid elimination, addressing both the timing precision and implementation complexity issues
2Loss of time
If conventional activation methods are used, then activation timing may be guessed, but precision deteriorates due to lack of accurate liquid fluid detection
Solution Approach 1:
The system continuously monitors exhaust temperature and mass flow, using this feedback to update the elimination time function calculation. This real-time feedback mechanism allows precise determination of when liquid fluid has been eliminated from the exhaust stream, enabling accurate sensor activation timing without excessive delay
Solution Approach 2:
The patent changes the approach from guessing activation timing to calculating it based on physical parameters (temperature and mass flow). The elimination time function uses these parameters to determine the exact moment when liquid fluid has evaporated or been removed, providing precise activation timing
3Ease of manufacture
If conventional activation methods are used, then implementation may be simple, but complexity increases due to extensive calibration requirements
Solution Approach 1:
The patent extracts the essential parameters needed for liquid fluid detection (temperature and mass flow) from the complex calibration process. By focusing only on these two measurable parameters and using the elimination time function, the system removes the need for extensive calibration across different engine types while maintaining accuracy
Solution Approach 2:
The elimination time function is designed to be universal, working across different engine types and exhaust treatment systems without requiring specific calibration. The function uses fundamental physical relationships between temperature, mass flow, and liquid fluid evaporation, making it applicable to multiple systems with a single implementation
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 provides a reliable and accurate activation of sensors, reducing the risk of damage and optimizing exhaust treatment system control, while being cost-effective and less complex.
Implementation Method 1
Water will in this document generally be used as an example of a fluid possibly being present in the exhaust stream, in gaseous/vaporized state and/or in liquid state. However, the herein described invention and its embodiments may be used for handling essentially any fluid initially being present in the exhaust treatment system
Implementation Method 2
After the engine is started, the exhaust gas starts to warm up the system to above the dew point temperature, and the liquid fluid in the system therefore starts to evaporate
Implementation Method 3
if liquid water in the exhaust stream hits the sensors, an abrupt temperature drop from e.g. 850 °C to below 100 °C will occur. The sensors may hereby break, e.g. by cracking, due to this steep temperature gradient
Data Source
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AI summary
A method and a system for control of an activation of at least one fluid sensitive sensor of an exhaust treatment system arranged for treating an exhaust stream from an engine are presented. The method includes: - determining at least one exhaust temperature Texh and at least one exhaust mass flow Mexh for the exhaust stream; - determining if there is liquid fluid present in the exhaust stream at the at least one fluid sensitive sensor, respectively, based on: - at least one elimination time function f(Texh, Mexh), wherein the at least one elimination time function f(Texh,Mexh) is based on the at least one determined exhaust temperature Texh and the at least one determined exhaust mass flow Mexh; and -a corresponding lengths of at least one time period tfree-of-liquid needed to eliminate a predetermined amount of liquid fluid from the exhaust stream; and - controlling an activation of said at least one fluid sensitive sensor based on the determination of if there is liquid fluid present in the exhaust treatment system at the at least one fluid sensitive sensor.