Exhaust Pipe Baffle Prevents Urea Penetration Into Catalyst Support
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Solution Overview
Problem
Existing exhaust pipe systems with urea solution injectors for reducing agents in internal combustion engines face issues where the urea solution adheres to the pipe walls, penetrates support members, and causes expansion, leading to stress on exhaust purification catalysts, potentially damaging them.
Innovation Solution
An exhaust pipe design featuring a baffle portion on the internal surface upstream of the catalyst to prevent reducing agent penetration, with an enlarged diameter section and a cushioning member between the baffle and catalyst, ensuring the reducing agent does not reach the support member, thus preventing damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a urea solution injector is provided on the upstream side of the exhaust passage to supply reducing agent to the exhaust purification catalyst, then the NOx purification performance is improved, but the urea solution adheres to the pipe wall and penetrates the support member causing expansion and potential catalyst damage
Solution Approach 1:
The exhaust passage is divided into a first passage and a second passage by the baffle portion. The first passage allows exhaust gas to flow while the second passage is positioned downstream of the baffle. This segmentation prevents the reducing agent injected upstream from penetrating through the support member into the catalyst, while still allowing the catalyst to receive sufficient reducing agent for NOx purification through the controlled flow path in the second passage.
Solution Approach 2:
The baffle portion acts as an intermediary structure between the upstream injection point and the catalyst. It selectively blocks the reducing agent from reaching the support member while allowing exhaust gas to pass through to the catalyst in the second passage. This intermediary structure prevents the harmful penetration effect while maintaining the beneficial purification function.
2Productivity
If the reducing agent is supplied to the exhaust purification catalyst via injection upstream, then the reductive reaction efficiency is improved, but the adhered urea solution collects at the bottom and flows downstream potentially damaging the catalyst
Solution Approach 1:
The exhaust passage is segmented by the baffle portion into upstream and downstream sections. The baffle blocks the collecting urea solution at the bottom from flowing downstream to the catalyst, while allowing the exhaust gas containing the necessary reducing agent to pass through to the catalyst in the second passage. This maintains reductive reaction efficiency while protecting catalyst integrity.
3Reliability
If the support member is made more robust to prevent expansion, then the catalyst protection is improved, but the exhaust gas flow resistance increases and purification efficiency decreases
Solution Approach 1:
The harmful function of the support member (potential expansion from reducing agent penetration) is eliminated by preventing the reducing agent from reaching it in the first place through the baffle portion. This allows the support member to maintain its original design with optimal flow characteristics, without needing additional robustness that would increase flow resistance. The extraction of the harmful interaction preserves both catalyst protection and flow efficiency.
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
Effectively prevents reducing agent penetration into the support member, reducing the risk of catalyst damage and maintaining efficient ammonia generation and NOx purification without affecting exhaust gas flow.
Implementation Method 1
a baffle portion for preventing the reducing agent from penetrating the exhaust gas purification catalyst is provided on the portion of the internal surface of the exhaust pipe, which is upstream side of the exhaust gas purification catalyst
Implementation Method 2
the NOx in the exhaust gas can be reduced by promoting the reductive reaction of the NOx with ammonia (NH3) that is supplied as a reducing agent
Implementation Method 3
A selective reduction NOx catalyst (hereinafter, SCR) and an occlusion reduction NOx catalyst (hereinafter, LNT), for example, are well know as an exhaust purification catalyst that reduces and purifies nitrogen compounds (hereinafter, NOx) contained in exhaust gas
Implementation Method 4
part of the injected urea solution is not hydrolyzed in the exhaust gas and adheres on the inside wall surface of the exhaust pipe
Implementation Method 5
the exhaust pipe may include a cushioning member, which is provided between the baffle portion and the exhaust gas purification catalyst
Implementation Method 6
the exhaust pipe may include an enlarged diameter portion formed in the longer internal diameter than the upstream side, and the exhaust gas purification catalyst may be provided on the internal surface of the enlarged diameter portion
Data Source
AI summary
An exhaust gas purification catalyst, using a reducing agent, is provided on an inside of an exhaust pipe via a support member. A baffle portion for preventing the reducing agent from penetrating the exhaust gas purification catalyst is provided on a portion of an internal surface of the exhaust pipe, which is upstream of the exhaust gas purification catalyst.