Three-Valve Hydrocarbon Trap Routing for Cold-Start Emissions
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Solution Overview
Problem
Existing exhaust gas purifying catalysts in internal combustion engines have low conversion efficiency during cold start conditions, leading to residual pollutants that are difficult to remove effectively.
Innovation Solution
A system comprising a close-coupled catalyst, an underbody catalyst, and a hydrocarbon trap, along with a heat exchanger and liquid water knockout, utilizing a three-valve configuration to dynamically adjust the exhaust flow path through these components to reduce emissions across varying engine conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If catalysts are heated during cold start phase to increase pollutant conversion, then conversion efficiency is improved, but residual pollutants remain and system complexity increases due to additional heating components
Solution Approach 1:
The exhaust system uses the engine's own exhaust heat to warm up the catalysts without requiring external heating components. The close-coupled catalyst is positioned to receive hot exhaust directly from the engine, and the hydrocarbon trap is warmed by the same exhaust flow, enabling self-heating and reducing system complexity while maintaining high conversion efficiency during cold start
2Productivity
If hydrocarbon trap is activated too early during cold start, then emissions reduction is improved, but premature desorption occurs reducing overall efficiency
Solution Approach 1:
The close-coupled catalyst is positioned upstream to first warm up and begin pollutant conversion before the hydrocarbon trap is activated. This preliminary action ensures that the exhaust is sufficiently heated and the downstream catalyst is ready to handle hydrocarbons when they reach the trap, preventing premature desorption and maintaining stable conversion efficiency throughout the cold start phase
3Productivity
If multiple catalysts are used to reduce pollutants, then emissions reduction is improved, but device complexity and cost increase
Solution Approach 1:
The exhaust treatment system is segmented into two functional zones: a close-coupled catalyst positioned near the engine for initial pollutant conversion and heating, and a downstream underbody catalyst with hydrocarbon trap for secondary treatment. This segmentation allows each component to perform its specific function optimally while maintaining a relatively simple overall system architecture that effectively reduces multiple types of pollutants
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 reduces emissions by optimizing the operation of the hydrocarbon trap and underbody catalyst, preventing premature desorption of hydrocarbons and maintaining high conversion efficiency throughout different engine temperatures.
Implementation Method 1
a close-coupled catalyst with an underbody catalyst and a hydrocarbon trap disposed downstream of the close-coupled catalyst
Implementation Method 2
The device includes a heat exchanger and a liquid water knockout disposed downstream of the close-coupled catalyst
Implementation Method 3
a hydrocarbon trap disposed downstream of the close-coupled catalyst
Data Source
AI summary
A device for reducing emissions from an internal combustion engine having a close-coupled catalyst including an underbody catalyst and a hydrocarbon trap disposed downstream of the close-coupled catalyst. The device includes a heat exchanger and a liquid water knockout disposed downstream of the close-coupled catalyst. The device includes a three-valve system configured to dynamically adjust a flow path of exhaust from the internal combustion engine through the underbody catalyst or both the underbody catalyst and the hydrocarbon trap to reduce emissions. A method for reducing emissions including feeding an exhaust gas from the internal combustion engine to the close-coupled catalyst, producing a catalyzed exhaust gas. The method includes flowing the catalyzed exhaust gas from the close-coupled catalyst to the three-valve system.