Ceramic-Metal Diffusing Member for Exhaust Gas Purification
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Solution Overview
Problem
Existing exhaust gas purification systems using static mixers or swirlers in diesel engines face issues with temperature reduction and corrosion from urea solution by-products, leading to inefficient NOx reduction in the SCR system.
Innovation Solution
A diffusing member composed of a ceramic and metal combination, where the ceramic member surrounds the metal member, providing excellent heat resistance and corrosion protection, is used to maintain exhaust gas temperature and prevent corrosion, allowing for effective NOx reduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a metal static mixer is used to mix exhaust gas, then mixing efficiency is improved, but exhaust gas temperature decreases and corrosion resistance deteriorates
Solution Approach 1:
The patent applies composite materials by combining ceramic and metal components in a single mixer structure. The ceramic portion contacts the exhaust gas to maintain temperature, while the metal portion provides structural support and enables welding to the exhaust pipe. This composite approach resolves the contradiction by allowing efficient mixing through the metal structure while preventing heat absorption and corrosion through the ceramic surface.
2Reliability
If a plastic static mixer is used to mix exhaust gas, then corrosion resistance is improved, but heat resistance deteriorates and installation complexity increases
Solution Approach 1:
The patent uses a composite structure where ceramic material provides both the corrosion resistance needed to withstand urea solution by-products and the heat resistance required to maintain exhaust gas temperature. The metal component is strategically used only for connection purposes, minimizing its exposure to corrosive and high-temperature environments while enabling straightforward welding installation.
3Productivity
If a mixer or swirler is used to generate swirl flow for mixing, then mixing efficiency is improved, but exhaust gas temperature decreases
Solution Approach 1:
The patent applies local quality by giving different portions of the mixer different material properties. The ceramic portion that directly contacts the exhaust gas has low thermal conductivity to minimize heat loss, while the metal connection portion has high thermal conductivity for structural integrity. The ceramic surface is specifically designed to withstand corrosion from urea by-products, creating localized functional zones that address different requirements simultaneously.
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 ceramic-metal diffusing member effectively suppresses temperature decrease and corrosion, ensuring efficient NOx reduction in the SCR system by maintaining exhaust gas temperature and preventing corrosion from urea solution by-products.
Implementation Method 1
the diffusing member includes a ceramic member and a metal member... suppresses a decrease in the exhaust gas temperature
Implementation Method 2
the diffusing member is disposed in an exhaust pipe to partially block exhaust gas flowing in from upstream of the exhaust pipe
Data Source
AI summary
The diffusing member of the present invention is disposed in an exhaust pipe to partially block exhaust gas flowing in from upstream of the exhaust pipe, the diffusing member including a ceramic member and a metal member, wherein the ceramic member surrounds the metal member in such a manner that the metal member is partially exposed, and the volume of the ceramic member constituting the diffusing member is larger than the volume of the metal member constituting the diffusing member.