NOx Occlusion Estimation via Lean Release Subtraction
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Solution Overview
Problem
Current methods for estimating NOx occlusion amount in NOx-occlusion-reduction-type catalysts are inaccurate due to the lack of consideration for NOx release during lean operations, leading to inefficient NOx purge processes and increased fuel consumption.
Innovation Solution
A device and method that calculates the actual NOx occlusion amount by acquiring catalyst temperature, estimating provisional occlusion, calculating lean-time NOx release, and subtracting this release from the provisional amount to determine the actual occlusion, thereby improving estimation accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the NOx occlusion amount is estimated by calculating the total NOx occlusion amount based on catalyst-inlet NOx amount and catalyst temperature without considering NOx release during lean operation, then the calculation method is simple, but the estimation accuracy deteriorates because the estimated value is greater than the actual NOx occlusion amount
Solution Approach 1:
The estimation method is segmented into distinct components: total NOx occlusion amount calculation and NOx release amount calculation. Each component handles a specific aspect of the NOx management process, allowing for more accurate individual calculations that collectively improve overall estimation accuracy without excessive complexity
Solution Approach 2:
The system incorporates feedback by using detected NOx amounts and catalyst temperature to continuously update and refine the NOx occlusion amount estimation. This feedback mechanism allows the system to adjust estimates based on actual operating conditions, improving accuracy while maintaining a manageable level of complexity through adaptive rather than purely computational approaches
2Reliability
If the NOx purge is implemented based on an overestimated NOx occlusion amount, then the catalyst can be fully regenerated, but the fuel consumption increases due to useless fuel consumption
Solution Approach 1:
The system applies partial action by performing NOx purge only when the actual NOx occlusion amount reaches necessary levels, rather than always purging when the total occlusion amount is high. This selective approach avoids excessive fuel consumption while ensuring catalyst regeneration occurs when truly needed, balancing reliability with energy efficiency
Solution Approach 2:
The system changes the decision parameter from total NOx occlusion amount to actual NOx occlusion amount (after subtracting release amount). This parameter change allows for more precise control of the purge timing, ensuring regeneration occurs at optimal moments rather than based on inflated estimates, thereby reducing unnecessary fuel consumption
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
Enhances the precision of NOx occlusion amount estimation, optimizing NOx purge processes and reducing fuel consumption by accounting for NOx release during lean operations.
Implementation Method 1
When the exhaust is in a lean atmosphere, the NOx-occlusion-reduction-type catalyst occludes NOx contained in the exhaust
Implementation Method 2
when the exhaust is in a rich atmosphere, the NOx-occlusion-reduction-type catalyst detoxifies and releases the occluded NOx with hydrocarbon contained in the exhaust by reduction and purification
Implementation Method 3
the NOx-occlusion-reduction-type catalyst detoxifies and releases the occluded NOx with hydrocarbon contained in the exhaust by reduction and purification
Implementation Method 4
catalyst temperature acquisition means for acquiring a catalyst temperature of the NOx-occlusion-reduction-type catalyst
Data Source
AI summary
An exhaust purification system includes a NOx-occlusion-reduction-type catalyst that occludes NOx in exhaust in a lean state and reduces and purifies the occluded NOx in exhaust in a rich state, and a NOx purge rich control unit that executes NOx purge of reducing and purifying the occluded NOx by putting the exhaust into the rich state by fuel injection control, where a catalyst temperature of the NOx-occlusion-reduction-type catalyst is equal to or higher than a catalyst temperature threshold value and a NOx occlusion amount of the NOx-occlusion-reduction-type catalyst is equal to or higher than an NOx occlusion amount threshold value, and executes the NOx purge when the catalyst temperature is lower than a catalyst temperature threshold value.