Exhaust Gas Purification System Fuel Supply Control
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Solution Overview
Problem
In exhaust gas purification systems with NOx selective catalytic reduction catalysts and oxidation catalysts, fuel poisoning occurs due to high temperatures causing fuel components to flow into the NOx catalyst, leading to decreased NOx purification performance.
Innovation Solution
An exhaust gas purification system with adjustable fuel supply modes to control temperature and fuel concentration, using a first fuel supply unit for initial temperature raising and a second unit for maintaining target temperature, ensuring efficient oxidation and minimizing fuel reaching the NOx catalyst, thereby preventing fuel poisoning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If fuel is supplied into exhaust gas to raise temperature for filter regeneration, then the temperature of the oxidation catalyst increases to oxidize particulate matter, but fuel components may flow into the NOx selective catalytic reduction catalyst causing fuel poisoning
Solution Approach 1:
The patent divides the fuel supply process into two distinct stages: a first fuel supply mode for initial temperature raising, and a second fuel supply mode for maintaining target temperature. This segmentation allows optimization of fuel management at different temperature phases, preventing fuel poisoning while achieving filter regeneration.
Solution Approach 2:
The patent implements preliminary action by switching to the second fuel supply mode before fuel poisoning can occur. The control unit monitors temperature and fuel concentration, and proactively adjusts fuel supply strategy to maintain temperature without allowing excessive fuel components to reach the NOx catalyst.
2Temperature
If fuel supply is increased to maintain temperature, then the target temperature is sustained for complete particulate matter oxidation, but the concentration of fuel components in exhaust gas increases leading to fuel poisoning
Solution Approach 1:
The patent employs dynamic fuel supply control by switching between two fuel supply modes based on real-time temperature and fuel concentration conditions. The first mode uses higher fuel supply for temperature raising, while the second mode adjusts fuel supply to maintain temperature with lower fuel concentration, dynamically adapting to prevent fuel poisoning.
Solution Approach 2:
The patent changes the parameter of fuel supply concentration by implementing two distinct fuel supply modes. The first mode supplies fuel at a concentration suitable for rapid heating, while the second mode supplies fuel at a controlled concentration to maintain temperature without causing fuel poisoning, thereby optimizing the balance between temperature maintenance and fuel management.
3Reliability
If fuel supply mode is switched to prevent fuel poisoning, then the NOx purification performance is protected, but the temperature control precision may be affected
Solution Approach 1:
The patent implements feedback control by using the fuel concentration sensor to monitor fuel levels in the exhaust gas. The control unit receives feedback on both temperature and fuel concentration, and adjusts the fuel supply strategy accordingly, switching between the first and second fuel supply modes to maintain temperature while preventing fuel poisoning.
Solution Approach 2:
The patent introduces a fuel concentration sensor as an intermediary element that provides critical information about fuel levels in the exhaust gas. This intermediary allows the control unit to make informed decisions about fuel supply strategy, enabling precise temperature control while preventing fuel poisoning by detecting fuel concentration before it reaches dangerous levels.
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 system effectively suppresses fuel poisoning of the NOx selective catalytic reduction catalyst, maintaining NOx purification performance by optimizing fuel supply strategies based on temperature and catalyst conditions.
Implementation Method 1
a temperature rise control unit configured to carry out temperature raising processing which raises a temperature of exhaust gas flowing into the exhaust gas purification device by supplying fuel to the exhaust gas and oxidizing the supplied fuel in the oxidation catalyst
Implementation Method 2
the NOx in the exhaust gas is selectively reduced by the supply of ammonia
Data Source
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AI summary
An exhaust gas purification system is provided with a first fuel supply unit to supply fuel to exhaust gas flowing in an exhaust passage of the internal combustion engine by means of a supply valve arranged in the exhaust passage, and a second fuel supply unit to supply fuel to exhaust gas to be discharged to the exhaust passage by adjusting a fuel injection condition in the internal combustion engine, wherein in a temperature raising stage of the NOx selective catalytic reduction catalyst associated with the exhaust gas temperature raising processing, first control is performed in which fuel is supplied by the first fuel supply unit, and in a temperature holding stage of the NOx selective catalytic reduction catalyst associated with the exhaust gas temperature raising processing, at least second control is performed in which the ratio of an amount of fuel supply by the second fuel supply unit with respect to an amount of fuel supply by the first fuel supply unit becomes higher in comparison with that when performing the first control.