Oxidation Catalyst Quenching Prevention via Dynamic Injection
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Solution Overview
Problem
Exhaust gas treatment systems face degradation over time due to loss of active catalyst material and high temperatures, leading to increased light-off temperatures and quenching of oxidation catalysts, resulting in reduced performance and excessive hydrocarbon slip.
Innovation Solution
A method is implemented to sense the status of the oxidation catalyst and reduce the acceleration rate of hydrocarbon injection when quenching is detected, preventing excessive hydrocarbon slip and minimizing temperature gradients by adjusting the injection rate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the acceleration rate of hydrocarbon injection is increased to minimize regeneration time, then productivity is improved, but the oxidation catalyst may become quenched leading to reduced reliability
Solution Approach 1:
The system dynamically adjusts the acceleration rate of hydrocarbon injection based on real-time monitoring of oxidation catalyst temperature and hydrocarbon slip. When quenching is detected, the acceleration rate is reduced; when the catalyst is not quenched, the maximum acceleration rate is used. This dynamic adaptation resolves the contradiction by allowing high productivity when conditions permit while protecting reliability when the catalyst is vulnerable.
Solution Approach 2:
The system implements feedback control by monitoring oxidation catalyst temperature and hydrocarbon slip levels, then adjusting the hydrocarbon injection acceleration rate accordingly. This closed-loop feedback mechanism enables the system to maintain optimal regeneration speed while preventing catalyst quenching, thus resolving the contradiction between productivity and reliability.
2Temperature
If hydrocarbon injection rate is rapidly increased to heat the oxidation catalyst, then temperature is improved, but extreme temperature gradients are generated causing harmful thermal stress
Solution Approach 1:
The acceleration rate of hydrocarbon injection is dynamically adjusted based on real-time temperature monitoring. When the catalyst is cold and can accept rapid heating, maximum acceleration is applied. When temperature approaches light-off or quenching is detected, the acceleration rate is reduced. This dynamic control achieves rapid heating while minimizing harmful temperature gradients.
Solution Approach 2:
The system changes the parameter of injection acceleration rate based on temperature conditions. By adjusting this parameter dynamically rather than using a fixed rate, the system optimizes heating speed while preventing excessive temperature gradients that would cause thermal stress and damage to the catalyst substrate.
3Manufacturing precision
If the oxidation catalyst light-off temperature increases due to degradation, then manufacturing precision deteriorates, but quenching risk increases leading to reduced performance
Solution Approach 1:
The system adapts to changing catalyst characteristics by monitoring actual light-off temperature shifts due to degradation. It adjusts the hydrocarbon injection strategy and acceleration rates to compensate for elevated light-off temperatures, maintaining reliable hydrocarbon oxidation performance despite manufacturing precision deterioration from catalyst aging.
Solution Approach 2:
Through continuous monitoring of catalyst temperature and hydrocarbon slip, the system detects when light-off temperature has increased due to degradation. This feedback triggers adjustments in injection parameters to ensure the catalyst reaches and maintains effective operating temperature, preserving reliability despite manufacturing precision loss.
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 extends the useful life of the oxidation catalyst and other exhaust gas treatment system components by preventing quenching and reducing extreme temperature gradients, thereby maintaining system performance.
Implementation Method 1
The additional hydrocarbons injected into the flow of exhaust gas may be ignited to further heat the flow of exhaust gas
Implementation Method 2
As the exhaust gases traverse the active catalyst layer, carbon monoxide, gaseous hydrocarbons and liquid hydrocarbon particles, i.e., unburned fuel and/or oil, are oxidized
Implementation Method 3
carbon monoxide, gaseous hydrocarbons and liquid hydrocarbon particles, i.e., unburned fuel and/or oil, are oxidized
Data Source
AI summary
A method of controlling an exhaust gas treatment system of a vehicle includes detecting a request to regenerate a particulate filter, and injecting hydrocarbons at an injection rate into a flow of exhaust gas upstream of an oxidation catalyst to heat the oxidation catalyst. The injection rate is increased at a current acceleration rate, and the current acceleration rate is reduced to define a reduced acceleration rate when the oxidation catalyst is quenched.