Exhaust Aftertreatment Deposit Removal via Dynamic Urea Injection
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Solution Overview
Problem
Excessive deposits of reduction agent by-products in the exhaust aftertreatment system of internal combustion engines lead to deteriorated performance, increased NOx emissions, and poor fuel economy, due to incomplete decomposition of urea at varying temperatures.
Innovation Solution
A method involving a control unit that identifies a future operating sequence with distinct temporal portions, confirming its suitability, and executing a deposit removal dosage procedure by injecting a higher initial dosage of reduction agent followed by a significantly lower dosage, optimized to maintain efficient catalyst performance and prevent deposit buildup, thereby ensuring efficient decomposition and emission control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If a reduction agent is injected into the exhaust aftertreatment system to reduce NOx emissions, then emission performance is improved, but deposits accumulate on inner walls leading to deteriorated system performance
Solution Approach 1:
The control unit identifies a future operating sequence and confirms its suitability for deposit removal before executing the deposit removal dosage procedure. This preliminary identification and confirmation allows the system to proactively prevent deposit accumulation rather than reacting after deposits have formed, thereby maintaining system performance while continuing NOx reduction.
Solution Approach 2:
The system executes deposit removal dosage procedures periodically based on identified future operating sequences rather than continuously. By injecting reduction agent at strategically timed intervals when operating conditions are suitable, the system prevents deposit accumulation without the need for continuous high-level injection, thus maintaining both emission performance and system reliability.
2Reliability
If the reduction agent dosage is increased to prevent deposit accumulation, then deposit formation is reduced, but fuel consumption increases
Solution Approach 1:
Instead of continuously injecting reduction agent at excessive levels to prevent all deposit formation, the system applies partial action by injecting at optimized dosages only when future operating sequences indicate suitable conditions. This selective approach removes deposits effectively while minimizing the total reduction agent consumption and associated fuel penalty.
Solution Approach 2:
The system dynamically adjusts the reduction agent dosage based on identified operating sequences and confirmed suitability conditions. By changing the injection parameters (dosage level, timing, duration) according to actual operating conditions rather than using fixed high dosages, the system achieves effective deposit removal with minimized fuel consumption.
3Object-generated harmful factors
If continuous high dosage of reduction agent is injected to maintain catalyst performance, then emission control is maintained, but deposit buildup occurs in downstream portions
Solution Approach 1:
The injection strategy is segmented into different phases: normal operation dosage for NOx control and deposit removal dosage for maintaining system performance. The control unit identifies specific time periods within the operating sequence and applies different dosages appropriately, preventing deposit buildup in downstream portions while maintaining upstream catalyst performance.
Solution Approach 2:
The reduction agent dosage is made dynamic rather than static. The system continuously monitors operating conditions, identifies future sequences, and adjusts injection levels in real-time based on confirmed suitability for deposit removal. This dynamic adjustment allows the system to respond to changing conditions and prevent deposit accumulation without sacrificing NOx control.
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 effectively reduces deposits without negatively impacting fuel efficiency, maintains emission performance, and reduces the need for regeneration events, improving engine uptime by ensuring optimal temperature conditions for deposit removal.
Implementation Method 1
the decomposition of urea is largely affected by the temperature in the exhaust aftertreatment system, in particular the temperature in the portion of the exhaust aftertreatment system where the reduction agent is injected
Implementation Method 2
The reduction agent operates with a component of the exhaust aftertreatment system, e.g., a selective catalytic reduction catalyst, to reduce the amount of NOx
Data Source
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AI summary
The invention relates to a method (400) for reducing deposits related to a reduction agent (204) in a portion (212) of an exhaust aftertreatment system (200) of an internal combustion engine (102), said exhaust aftertreatment system (200) comprising an injector (202) for injecting the reduction agent (204) into said exhaust aftertreatment system (200), and said portion (212) of said exhaust aftertreatment system (200) being located downstream of said injector (202), as seen in an intended direction of flow (208) of exhaust gas in said exhaust aftertreatment system (200), said method comprising the steps of: a) identifying a future operating sequence (300) for said internal combustion engine (102), said future operating sequence (300) comprising a first temporal portion (t1) and a second temporal portion (t2), said second temporal portion (t2) being subsequent to said first temporal portion (t1), b) performing a confirmation procedure comprising: ∘ confirming that said future operating sequence (300) is suitable for reducing said deposits and ∘ confirming that said internal combustion engine (102) operates in accordance with said precedingly identified future operating sequence (300), c) in response to said confirmation procedure being affirmative, executing a deposit removal dosage procedure comprising controlling said injector (202) such that a first dosage (d1) of reduction agent (204) is injected into said exhaust aftertreatment system (200) during at least a part of said first temporal portion (t1) and that a second dosage (d2) of reduction agent (204) is injected into said exhaust aftertreatment system (200) during at least a part of said second temporal portion (t2) said second dosage (d2) being smaller than said first dosage (d1).