SCR Urea Injector Flow Detection via Thermal Analysis
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Solution Overview
Problem
Existing reagent dosing systems, such as SCR systems, face challenges in detecting blockages in urea injectors due to deposits, as traditional methods rely on valve movement detection, which is unreliable when nozzles become blocked, and most systems fail to detect lack of flow caused by blocked nozzles orifices.
Innovation Solution
A method involving temperature analysis before and after injector activation to determine reductant flow by comparing temperature changes and gradients, using a temperature sensor to assess the cooling effect of reductant flow through the injector, distinguishing between normal and blocked conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional valve movement detection methods are used to monitor injector operation, then the system can detect injector activation, but it cannot reliably detect blocked nozzles or lack of reductant flow
Solution Approach 1:
The patent replaces mechanical valve movement detection with thermal field analysis. By monitoring temperature changes in the injector housing and surrounding components during and after activation, the system detects reductant flow conditions without relying on mechanical position sensing, thereby overcoming the limitation of traditional methods in detecting blocked nozzles.
Solution Approach 2:
The patent introduces temperature as an intermediary parameter to indirectly measure reductant flow. Instead of directly observing the valve or nozzle, the system uses temperature changes in the injector assembly as a mediator to infer flow conditions, enabling detection of blockages through thermal field analysis rather than direct mechanical observation.
2Reliability
If the injector is cooled via a cooling system with cooling fluid, then the injector operates reliably, but detecting blocked nozzles becomes more difficult as the cooling effect masks flow issues
Solution Approach 1:
The patent utilizes changes in temperature parameters during injector activation cycles to detect flow conditions. By monitoring how the cooling system's thermal field evolves during and after reductant injection, the system identifies deviations from normal thermal behavior that indicate blocked nozzles, transforming the cooling effect from a masking factor into a detection tool.
Solution Approach 2:
The system implements feedback by continuously monitoring temperature changes during injector operation and comparing them against expected thermal profiles. When the actual temperature evolution deviates from the predicted pattern based on previous normal operation, the system identifies this as indicative of a blockage, using the cooling system's own thermal response as feedback for diagnosis.
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
Effectively identifies blocked or partially blocked urea injectors by analyzing temperature profiles and gradients, providing a reliable indication of reductant flow issues, thereby preventing system failures and improving reagent dosing accuracy.
Implementation Method 1
analyzing changes in the said determined measure of temperatures... analyzing the flow of reductant through said injector consequential to said activation by analyzing changes in the said determined measure of temperatures
Data Source
AI summary
In a selective catalytic reductant dosing system including a reductant injector adapted to inject liquid reductant into an exhaust line, a method of analyzing flow of reductant through the injector includes determining a measure of the temperature of the injector prior to activation of the injector. The method also includes activating the injector and determining a measure of the temperature of the injector subsequent to activation of the injector. The method also includes analyzing the flow of reductant through the injector consequential to the activation by analyzing changes in the measure of temperature of the injector prior to activation and the measure of temperature of the injector subsequent to activation.