Urea Adsorbing Holding Sealing Material for SCR Exhaust Systems
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Solution Overview
Problem
Conventional holding sealing materials in exhaust gas purifying apparatuses for urea SCR systems face challenges in maintaining holding strength over long periods due to urea crystallization and permeation, leading to reduced effectiveness and operational issues.
Innovation Solution
A holding sealing material with a mat shape, featuring an adsorption portion and a holding portion separated by a space, where the adsorption portion is designed to absorb urea, preventing its permeation into the holding portion, and the holding portion maintains high strength by minimizing urea crystallization, even under high temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional holding sealing material is used in a urea SCR system, then the exhaust gas treating body is protected from damage and exhaust gas leakage is prevented, but urea crystallization and permeation occur over time leading to reduced holding strength
Solution Approach 1:
The holding sealing material is divided into two distinct functional portions: an adsorption portion configured to adsorb urea and a holding portion configured to hold the exhaust gas treating body. This segmentation allows each portion to perform its specific function optimally, preventing urea from reaching the holding portion and causing crystallization while maintaining strong protective function.
Solution Approach 2:
The adsorption portion acts as an intermediary barrier between the urea spray and the holding portion. It selectively adsorbs urea molecules, preventing them from permeating through to the holding portion where they would cause crystallization and strength degradation. This intermediary function extends the service life while maintaining holding strength.
2Productivity
If urea is sprayed toward the exhaust gas treating body for NOx conversion, then NOx reduction is achieved, but urea permeates through the holding sealing material causing crystallization and loss of holding strength
Solution Approach 1:
Different portions of the holding sealing material are given different local qualities: the adsorption portion has high urea adsorption capacity to intercept urea molecules, while the holding portion maintains high temperature resistance and mechanical strength to securely hold the exhaust gas treating body. This local differentiation allows simultaneous achievement of NOx conversion support and long-term structural reliability.
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 solution effectively prevents urea permeation and crystallization, ensuring high holding strength and operational efficiency of the exhaust gas purifying apparatus over extended periods, reducing the need for frequent refilling and maintaining NOx conversion performance.
Implementation Method 1
an adsorption portion configured to adsorb urea
Implementation Method 2
preventing urea crystallization
Data Source
AI summary
A holding sealing material has a mat shape and includes an adsorption portion, a holding portion, and a coupling portion. The adsorption portion is configured to adsorb urea and has a width and a longer side face extending along a longitudinal direction of the holding sealing material. The holding portion is configured to hold an exhaust gas treating body and has another width and another longer side face extending along the longitudinal direction. The width of the adsorption portion is smaller than the width of the holding portion. The longer side face of the adsorption portion faces the longer side face of the holding portion via a space. The coupling portion connects the adsorption portion and the holding portion.