SCR Catalyst Management via Periodic Filter Regeneration
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Solution Overview
Problem
The temperature fluctuations in the exhaust line of internal combustion engines can lead to crystallization of reducing agents in the SCR catalyst system, reducing the efficiency of nitrogen oxide treatment and causing sporadic emissions, while unburnt hydrocarbons stored at low temperatures limit the SCR catalyst's effectiveness.
Innovation Solution
A method for managing the powertrain that includes periodic regeneration of the particulate filter based on independent criteria, such as time and distance, to regulate the quantity of reducing agent crystals and unburnt hydrocarbons, using sensors and estimation algorithms to determine and reset thresholds, thereby preventing the accumulation of crystals and hydrocarbons.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the temperature of the exhaust line is kept low to improve fuel economy, then fuel consumption is reduced, but the reducing agent crystallizes and hydrocarbons accumulate on the SCR catalyst
Solution Approach 1:
The patent applies periodic action by implementing periodic regeneration cycles of the particulate filter. These regeneration events are triggered based on accumulated operation time or distance, independent of soot load. During each regeneration event, the exhaust temperature is temporarily increased to vaporize reducing agent crystals and oxidize accumulated hydrocarbons on the SCR catalyst, thereby maintaining SCR efficiency while allowing low-temperature operation between regenerations for fuel economy.
2Object-affected harmful factors
If the injection of reducing agent is limited below a temperature threshold to prevent crystallization, then crystal formation is reduced, but the efficiency of nitrogen oxide treatment drops
Solution Approach 1:
The patent applies preliminary action by proactively removing reducing agent crystals and hydrocarbons from the SCR catalyst through periodic regeneration events before they can significantly accumulate and impair SCR performance. This allows the system to maintain reducing agent injection at low temperatures without worrying about crystal accumulation, as the crystals are periodically cleared away in advance.
3Reliability
If the exhaust line is heated quickly to prevent crystal formation and hydrocarbon accumulation, then SCR catalyst efficiency is maintained, but fuel consumption increases
Solution Approach 1:
The system uses periodic regeneration events triggered by operation time or distance counters rather than continuous high-temperature operation. This allows the exhaust line to operate at low temperatures for fuel economy between regeneration events, while periodically raising the temperature to clear accumulations, thus resolving the contradiction between maintaining SCR efficiency and minimizing fuel consumption.
4Productivity
If periodic regeneration is triggered based on soot load in the particulate filter, then filter maintenance is optimized, but reducing agent crystals and hydrocarbons accumulate on the SCR catalyst
Solution Approach 1:
The patent segments the regeneration trigger criteria into two independent components: soot load-based triggering for particulate filter maintenance, and time/distance-based triggering for SCR catalyst maintenance. This segmentation allows the system to address both the filter's soot removal needs and the SCR catalyst's crystal/hydrocarbon removal needs through separate, independent triggering mechanisms, resolving the contradiction between optimized filter maintenance and SCR catalyst protection.
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 ensures that the SCR catalyst operates efficiently by preventing the formation of reducing agent crystals and unburnt hydrocarbons, maintaining effective nitrogen oxide treatment and reducing harmful emissions.
Implementation Method 1
these hydrocarbons stored on the SCR catalyst, emitted by the engine or sent by an additional injector placed in the exhaust line, are only oxidized above approximately 350 °C
Implementation Method 2
A step for regenerating the particulate filter can be implemented when a triggering condition taking into account the quantity of soot contained in the particle filter is verified
Implementation Method 3
If the temperature of the exhaust line at the SCR catalyst is too low (less than approximately 200 °C), the injected reducing agent may crystallize in the exhaust line and / or in the agent injector
Implementation Method 4
an SCR catalyst ensuring a selective catalytic reduction of nitrogen oxides by means of a suitable reducing agent (such as, for example, ammonia NH3)
Data Source
Figure 1~2
Figure 3
Figure 4~5
AI summary
According to the invention, the management of a motor vehicle power train includes a method for adjusting the amount (MC) of reducing agent crystals in an exhaust line (11) and/or in the injection device (13), and the amount (MH) of hydrocarbons contained in the catalyst (SCR), wherein the adjustment method includes periodic steps (E1) of regenerating the particle filter (20), which are each triggered on the basis of separate criteria of the amount (MP) of soot contained in the particle filter (20).