Diesel Exhaust Fluid Injector Cleaning via Superheated Gas
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Urea deposits on diesel-exhaust-fluid (DEF) injectors in internal combustion engines can lead to reduced performance and altered NOx emissions due to fouling, which existing systems fail to address effectively.
Innovation Solution
A method and system utilizing a controller to detect NOx levels and activate the DEF injector, coupled with fuel injection to generate superheated exhaust gas, which burns off urea deposits at the injector tip, thereby maintaining optimal spray pattern and NOx reduction efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the DEF injector operates continuously to reduce NOx emissions, then NOx reduction efficiency is improved, but urea deposits form on the injector tip causing fouling and performance degradation
Solution Approach 1:
The system implements periodic cleaning cycles where the DEF injector is temporarily deactivated and fuel is injected to generate superheated exhaust gas that burns off urea deposits. This periodic action alternates between normal NOx reduction operation and cleaning operation, preventing cumulative fouling while maintaining overall emission control effectiveness
Solution Approach 2:
The system converts the harmful effect of urea deposits into a beneficial cleaning mechanism by using fuel injection to create superheated exhaust gas. This superheated gas, which would normally be wasted, is instead utilized to thermally clean the injector tip, transforming a harmful deposition process into a beneficial removal process
2Reliability
If fuel injection is increased to clean urea deposits, then injector cleanliness is improved, but engine emissions and energy consumption increase
Solution Approach 1:
The system uses the engine's own exhaust gas, heated by the engine's normal combustion process, to clean the DEF injector. The exhaust gas is directed through the injector tip using the existing exhaust manifold structure, eliminating the need for separate cleaning equipment or additional energy input beyond normal engine operation
Solution Approach 2:
The exhaust system serves multiple functions: it carries emissions control functions through the SCR catalyst and simultaneously provides the cleaning function for the DEF injector by directing superheated exhaust gas through the injector tip. This multi-functionality eliminates the need for separate cleaning systems
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
The solution effectively cleans urea deposits on DEF injectors, ensuring consistent NOx emission control and preventing performance degradation, while also providing a mechanism to alert for potential service needs based on long-term adaption factor thresholds.
Implementation Method 1
regulating an injection of fuel upstream of the SCR to generate a stream of superheated exhaust gas and thereby clean the DEF injector
Implementation Method 2
regulating an injection of fuel upstream of the SCR to generate a stream of superheated exhaust gas
Data Source
AI summary
A method for controlling an exhaust after-treatment system connected to a diesel engine via a gas passage and having a diesel oxidation catalyst (DOC) and a “diesel-exhaust-fluid” (DEF) injector arranged downstream of the DOC and upstream of a selective catalytic reduction catalyst (SCR) includes detecting a flow of exhaust gas emitted by the engine into the gas passage. The method also includes detecting a level of nitrogen oxides (NOx) in the exhaust gas downstream of the SCR. The method additionally includes activating the DEF injector for a period of time to reduce the level of NOx to a predetermined NOx value. Furthermore, the method includes regulating an injection of fuel upstream of the DOC to clean the DEF injector via a stream of superheated exhaust gas if the period of time used to reduce the level of NOx to the predetermined NOx value is greater than a predetermined threshold value.