Exhaust Additive Control via Unburned Fuel Injection
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Solution Overview
Problem
Existing methods for correcting the supply of additives to exhaust gas streams from internal combustion engines often result in either excessive or insufficient additive levels, leading to undesired emissions of nitrogen oxides due to inaccuracies in measuring nitrogen oxide concentrations, which can be misinterpreted by sensors due to differences in sensor sensitivity between nitric oxides and nitrogen dioxide.
Innovation Solution
The method involves supplying unburned fuel upstream of an oxidation catalytic converter to reduce the oxidation of nitric oxide to nitrogen dioxide, allowing for accurate measurement and correction of additive supply based on the presence of nitric oxides only, ensuring that the additive is proportionally adjusted to match the actual occurrence of nitrogen oxides in the exhaust gas stream, thereby minimizing misinterpretation of sensor signals and achieving optimal reduction of nitrogen oxides.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If an additive is supplied to reduce nitrogen oxides in the exhaust gas stream, then nitrogen oxide emissions are reduced, but the additive supply may be inaccurate leading to either excessive or insufficient additive levels
Solution Approach 1:
The system uses a sensor to measure the actual nitrogen oxide concentration in the exhaust gas stream and feeds this information back to the control unit. The control unit compares the measured concentration with the target concentration and adjusts the additive supply rate accordingly, ensuring accurate additive dosing while maintaining low nitrogen oxide emissions
Solution Approach 2:
The patent replaces mechanical measurement methods with optical sensing technology. An optical sensor detects nitrogen oxide concentrations by measuring light absorption characteristics, providing precise non-contact measurement that enables accurate feedback control of additive supply without mechanical wear or contamination
2Measurement precision
If a sensor measures nitrogen oxide concentrations, then emission levels can be monitored, but sensor sensitivity differences between nitric oxides and nitrogen dioxide can cause misinterpretation of measurements
Solution Approach 1:
The system introduces a selective catalytic reduction converter as an intermediary component between the exhaust stream and the sensor. This converter selectively converts nitrogen dioxide to nitric oxide using a catalyst, ensuring that the sensor primarily detects nitric oxide signals which have consistent and predictable sensitivity characteristics, eliminating measurement errors caused by varying sensor responses to different nitrogen oxide species
Solution Approach 2:
The patent changes the chemical composition parameter of the exhaust gas stream by selectively converting nitrogen dioxide to nitric oxide before sensing. This parameter change ensures that the sensor operates in a regime where signal interpretation is unambiguous and accurate, as nitric oxide detection has well-established calibration curves and sensitivity characteristics
3Object-generated harmful factors
If unburned fuel is supplied upstream of the oxidation catalytic converter, then oxidation of nitric oxide to nitrogen dioxide is reduced, but this requires precise control of fuel injection timing and amount
Solution Approach 1:
The system performs preliminary action by injecting unburned fuel into the exhaust stream upstream of the oxidation catalytic converter before the nitric oxide oxidation reaction occurs. This timing is critical - the fuel is introduced at a specific point in the exhaust flow path where it can suppress the oxidation reaction without requiring complex real-time adjustment mechanisms, as the injection strategy is predetermined based on engine operating conditions
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 accurate correction of additive supply, reducing nitrogen oxide emissions by maintaining a low proportion of nitrogen dioxide relative to nitric oxide, allowing for precise control of additive levels and minimizing the risk of undesired emissions, such as ammonium, while ensuring the reduction catalytic converter operates effectively.
Implementation Method 1
supplying unburned fuel to said exhaust gas stream upstream said first aftertreatment component to reduce oxidation of nitric oxide into nitrogen dioxide
Implementation Method 2
The additive can be injected into the exhaust gas stream resulting from combustion in the internal combustion engine upstream the catalytic converter, and one common type of catalytic converter that is used in nitrogen oxide NOx reduction of this kind is Selective Catalytic Reduction (SCR) catalytic converters
Implementation Method 3
using a first sensor, measuring an occurrence of nitrogen oxides in said exhaust gas stream
Data Source
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AI summary
The present invention relates to a method for correcting a supply of additive to an exhaust gas stream (303) resulting from combustion in an internal combustion engine (101). A first aftertreatment component (310) being arranged for oxidation of nitric oxide (NO) into nitrogen dioxide (NO2), and a reduction catalytic converter (332) being arranged downstream said first aftertreatment component (310). Additive is supplied to said exhaust gas stream (303) for reduction of nitrogen oxides (NOx) in said reduction catalytic converter (332), the additive being supplied in proportion to an occurrence of nitrogen oxides (NOx) in said exhaust gas stream (303), said proportion being subject to correction. The method includes: - supplying unburned fuel to said exhaust gas stream (303) upstream said first aftertreatment component (310) to reduce oxidation of nitric oxide (NO) into nitrogen dioxide (NO2) in said first aftertreatment component (310), and - correcting said supply of additive to said exhaust gas stream (303) when supplying unburned fuel to said exhaust gas stream (303).