NOx Purge Interval Control for Diesel Catalyst
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Solution Overview
Problem
Frequent NOx purges in diesel engines at low catalyst temperatures lead to white smoke and fuel consumption deterioration due to excess unburned fuel, as existing systems fail to effectively manage NOx occlusion and catalyst activity.
Innovation Solution
An exhaust purification system and catalyst regeneration method that adjust the NOx purge interval based on the NOx occlusion amount and catalyst temperature, using an NOx purge control unit to extend the interval when the catalyst is inactive, preventing frequent purges and reducing fuel consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If frequent NOx purges are performed to recover NOx occlusion capacity, then the NOx purification rate is improved, but white smoke occurs and fuel consumption deteriorates when catalyst temperature is low
Solution Approach 1:
The patent changes the control parameter from fixed-time intervals to variable intervals based on NOx occlusion amount and catalyst temperature. When catalyst temperature is below activation temperature, the system extends the NOx purge interval even if NOx occlusion amount reaches the threshold, preventing frequent purges that cause white smoke and fuel consumption deterioration while maintaining NOx purification effectiveness.
Solution Approach 2:
The patent implements dynamic control of NOx purge timing by continuously monitoring both NOx occlusion amount and catalyst temperature. The purge interval is dynamically adjusted based on the combined state of these two parameters, making the system adaptive to changing operating conditions rather than using a static timing schedule.
2Use of energy by moving object
If NOx purge is delayed to avoid white smoke, then fuel consumption is improved, but the NOx purification rate deteriorates due to accumulated NOx occlusion
Solution Approach 1:
The patent changes the control parameter from fixed-time intervals to variable intervals based on NOx occlusion amount and catalyst temperature. When catalyst temperature is below activation temperature, the system extends the NOx purge interval even if NOx occlusion amount reaches the threshold, preventing frequent purges that cause white smoke and fuel consumption deterioration while maintaining NOx purification effectiveness.
Solution Approach 2:
The patent uses feedback from both NOx occlusion amount sensors and catalyst temperature sensors to determine purge timing. The system continuously monitors these parameters and adjusts the purge schedule accordingly, creating a closed-loop control system that balances NOx purification needs with fuel consumption and emission quality considerations.
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 prevents white smoke and fuel consumption deterioration by optimizing NOx purge timing according to NOx occlusion levels and catalyst activity, ensuring efficient exhaust gas purification.
Implementation Method 1
When the exhaust gas is under a lean atmosphere, the NOx occlusion reduction type catalyst occludes the NOx contained in the exhaust gas
Implementation Method 2
When the exhaust gas is under a rich atmosphere, the NOx occlusion reduction type catalyst detoxifies the occluded NOx through reducing and purifying with hydrocarbon contained in the exhaust gas
Implementation Method 3
an oxidation catalyst 31, an NOx occlusion reduction type catalyst 32
Data Source
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AI summary
Provided is an exhaust purification system including: an NOx occlusion reduction type catalyst (32), a catalyst temperature estimating unit (115), an NOx occlusion amount estimating unit (113), a regeneration control unit (100) that performs catalyst regeneration of bringing an exhaust gas into a rich state to recover NOx occlusion capacity of the NOx occlusion reduction type catalyst (32), an interval setting unit (118) that sets a target interval from the termination of the catalyst regeneration to a start of next catalyst regeneration, a catalyst regeneration start processing unit (110) that starts the next catalyst regeneration when the NOx occlusion amount is equal to or greater than a threshold and an elapsed time from the termination of the catalyst regeneration reaches the target interval, and an interval target value correcting unit (119) that extends and corrects the target interval based on the NOx occlusion amount when the catalyst temperature is lower than a predetermined catalyst activation temperature.