Segmented Exhaust Passages to Protect Auxiliary Catalysts
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Solution Overview
Problem
In existing exhaust systems, the auxiliary exhaust catalyst is subjected to thermal degradation due to a large flow of exhaust gas, particularly when the engine operates in regions with high exhaust gas flow amounts.
Innovation Solution
The exhaust system includes separate first and second exhaust passages with independent flow control, allowing the auxiliary exhaust catalyst to be positioned only in the first passage, reducing the flow through it and incorporating a flow amount adjustment unit and controller to manage exhaust gas distribution based on engine operation states.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the auxiliary exhaust catalyst is arranged in the exhaust passage upstream of the main exhaust catalyst, then the exhaust gas can be purified by the auxiliary exhaust catalyst before entering the main exhaust catalyst, but the auxiliary exhaust catalyst is subjected to thermal degradation when a large amount of exhaust gas passes through it
Solution Approach 1:
The exhaust passage is divided into multiple independent passages (first exhaust passage and second exhaust passage), with the auxiliary exhaust catalyst arranged only in the first exhaust passage. This segmentation allows selective routing of exhaust gas flow, enabling the system to bypass the auxiliary catalyst when high-temperature gas would cause thermal degradation, while still allowing purification when conditions are appropriate.
2Reliability
If the auxiliary exhaust catalyst is provided in the exhaust passage, then exhaust gas purification is enhanced, but the catalyst experiences thermal degradation in high-load operation regions
Solution Approach 1:
The system dynamically controls the flow distribution of exhaust gas between the first and second exhaust passages based on operating conditions. By adjusting which passage is active, the system adapts to varying engine loads and temperatures, protecting the auxiliary catalyst during high-temperature operation while maintaining purification capability during normal operation.
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 design inhibits thermal degradation of the auxiliary exhaust catalyst by controlling exhaust gas flow to minimize high-temperature exposure and efficiently warms up the catalyst, especially in cold states, while also effectively warming up the main catalyst.
Implementation Method 1
a plurality of exhaust catalysts which are provided in the exhaust passage and purify the exhaust gas
Implementation Method 2
the exhaust gas is caused to flow independently from the first exhaust passage and which is opened and/or closed by the second exhaust valve
Data Source
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AI summary
An exhaust passage 50 includes a first exhaust passage 51 which is opened and closed by a first exhaust valve 23, a second exhaust passage 52 through which exhaust gas is caused to flow independently from the first exhaust passage 51 and which is opened and closed by a second exhaust valve 24, and a third exhaust passage 53 in which the first exhaust passage 51 and the second exhaust passage 52 merge together, and exhaust catalysts include a main exhaust catalyst 60 which is provided in the third exhaust passage 53 and an auxiliary exhaust catalyst 61 which is arranged in the first exhaust passage 51 and has a smaller capacity than the main exhaust catalyst 60.