Cold Start Exhaust Purification via Residual Gas Extraction
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Solution Overview
Problem
Existing methods for reducing automobile exhaust gases during the cold start period, such as catalyst preheating and HC trap methods, face issues like excessive catalyst temperature, reduced durability, and high costs due to the use of precious metals, and fail to effectively control hydrocarbon emissions.
Innovation Solution
The method involves injecting air into the inlet end of a main catalyst unit and supplying oxygen to remove residual hydrocarbons from the exhaust pipe during engine shutdown, using an air pump and electronic control systems to manage the process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If catalyst preheating method is used to reach light-off temperature quickly, then hydrocarbon emissions are reduced, but catalyst temperature increases excessively during normal operation, decreasing catalyst life span
Solution Approach 1:
The patent extracts the harmful residual exhaust gases from the exhaust pipe and directs them to the catalyst unit for purification. By separating and processing only the harmful components (hydrocarbons, carbon monoxide, nitrogen oxides) that remain in the exhaust pipe after engine shutdown, the system achieves emission reduction without requiring excessive catalyst preheating that would damage the catalyst during normal operation.
Solution Approach 2:
The patent performs preliminary action by removing residual exhaust gases from the exhaust pipe during engine shutdown before the engine restarts. This preliminary purification action ensures that when the engine restarts, the catalyst unit is already prepared to handle the fresh exhaust gases effectively, reducing the need for high-temperature preheating during normal operation.
2Object-generated harmful factors
If HC trap method is used to adsorb hydrocarbons, then hydrocarbon emissions are reduced, but durability is reduced
Solution Approach 1:
The patent employs the catalyst unit's own oxygen storage capacity to purify hydrocarbons. The catalyst unit utilizes its inherent properties (oxygen storage and catalytic activity) to oxidize and convert hydrocarbons into harmless substances, eliminating the need for separate HC trap components that would reduce system durability.
Solution Approach 2:
The patent converts the harmful residual exhaust gases into a beneficial purification process. By directing residual exhaust gases containing hydrocarbons through the catalyst unit during engine shutdown, the system uses the catalyst's oxygen storage capacity to oxidize these harmful substances, transforming them into harmless water and carbon dioxide, thereby reducing emissions without adding durable components.
3Temperature
If precious metals are used to decrease light-off temperature of catalyst, then catalytic conversion efficiency is improved, but processing costs increase
Solution Approach 1:
The patent performs preliminary action by removing residual exhaust gases from the exhaust pipe during engine shutdown before the engine restarts. This preliminary purification action ensures that when the engine restarts, the catalyst unit is already prepared to handle the fresh exhaust gases effectively, reducing the need for high-temperature preheating during normal operation.
Solution Approach 2:
The patent changes the operational parameters by utilizing the catalyst unit's oxygen storage capacity and catalytic activity during engine shutdown to purify hydrocarbons. This parameter change allows the catalyst to operate effectively at lower temperatures without requiring excessive precious metal loading, as the residual exhaust gases provide a controlled environment for oxidation reactions.
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 significantly reduces hydrocarbon emissions by 25% during the initial cold start period, extending catalyst life and reducing processing costs by optimizing the use of oxygen for purification.
Implementation Method 1
supplying oxygen to remove residual hydrocarbons from the exhaust pipe
Data Source
AI summary
Disclosed herein is a method and apparatus for reducing exhaust gases in an initial cold start period, in which a main catalyst unit is connected to an engine through an exhaust pipe, including the steps of receiving signals for stopping engine operation from an engine, and removing engine exhaust gases remaining in an exhaust pipe located at an inlet of a main catalyst unit.