Exhaust Gas Purification via EGR Valve Control
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Solution Overview
Problem
Existing exhaust gas purification systems, including three-way catalysts and additional catalytic converters, face challenges in removing hydrocarbons at low temperatures during cold starting, leading to inefficient purification and release of adsorbed hydrocarbons before the catalyst light-off temperature is reached.
Innovation Solution
An apparatus and method utilizing oxygen sensors on an exhaust pipe downstream and upstream of a catalytic converter, along with an EGR valve, to control the recirculation of exhaust gas based on temperature and oxygen levels, ensuring efficient hydrocarbon removal by opening the EGR valve when the exhaust gas temperature is below a predetermined level and closing it when above, thereby enhancing purifying efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a hydrocarbon trap is used to adsorb hydrocarbons at low temperature, then hydrocarbon emissions are reduced, but purifying efficiency deteriorates when adsorbed hydrocarbons are released before catalyst light-off temperature
Solution Approach 1:
The system uses oxygen sensors to detect oxygen concentration in exhaust gas and provides feedback to the controller. The controller adjusts the EGR valve opening based on this feedback to control the amount of exhaust gas recirculation, thereby optimizing the balance between hydrocarbon adsorption and subsequent oxidation efficiency.
Solution Approach 2:
The system changes the temperature parameter of exhaust gas by controlling EGR valve opening. By adjusting the recirculation rate, the system controls the cooling effect and maintains exhaust gas temperature within an optimal range for both hydrocarbon adsorption by the trap and subsequent oxidation by the catalyst.
2Productivity
If EGR valve is opened to recirculate exhaust gas, then hydrocarbon purification efficiency is improved, but exhaust gas temperature decreases which may affect catalyst performance
Solution Approach 1:
The oxygen sensors provide continuous feedback on exhaust gas composition, allowing the controller to dynamically adjust EGR valve opening. This feedback mechanism enables the system to optimize the balance between hydrocarbon purification through recirculation and maintaining sufficient temperature for catalyst operation.
Solution Approach 2:
The EGR valve opening is dynamically adjusted based on real-time exhaust gas conditions detected by oxygen sensors. The system transitions from static EGR control to dynamic control, adapting the recirculation rate to current operating conditions to simultaneously achieve hydrocarbon removal and temperature maintenance.
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 recirculates exhaust gas to release adsorbed hydrocarbons at optimal temperatures, improving the overall purification efficiency of exhaust gases by ensuring complete conversion of harmful materials at the catalytic converter.
Implementation Method 1
a hydrocarbon trap and a three-way catalyst; Recently, technology for mounting an additional catalytic converter in addition to a three-way catalyst has been under development
Implementation Method 2
a hydrocarbon trap and a three-way catalyst
Data Source
AI summary
An apparatus and a method of purifying exhaust gas are provided. The apparatus for purifying exhaust gas may include: an exhaust pipe connected to an exhaust manifold of an engine; a catalytic converter mounted on the exhaust pipe and including a hydrocarbon trap and a three-way catalyst; an exhaust gas recirculation (EGR) pipe connecting downstream of the catalytic converter to an intake manifold of the engine; an EGR valve mounted on the EGR pipe; a first oxygen sensor mounted on the exhaust pipe downstream of the catalytic converter; a second oxygen sensor mounted on the exhaust pipe upstream of the catalytic converter; and a controller controlling an operation of the EGR valve.