Low Shear Mounting Mat for Exhaust Gas Treatment
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Solution Overview
Problem
Exhaust gas treatment devices, such as catalytic converters and diesel particulate traps, face frequent failures in low-temperature applications due to the loss of holding force in mounting mats caused by the liquefaction of organic binders, leading to inadequate pressure and shear strength, which is not effectively addressed by existing solutions.
Innovation Solution
A mounting mat comprising high-temperature resistant inorganic fibers, an organic binder that liquefies at elevated temperatures, colloidal inorganic oxide, and optionally intumescent materials, which reduces shear strain and maintains holding performance across a wide temperature range without significant thickness loss or shear strength reduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a mounting mat with organic binder is used to hold the fragile structure, then the mounting mat provides initial holding force and structural integrity at room temperature, but the organic binder liquefies at low temperatures (below 350°C) causing loss of shear strength and holding force
Solution Approach 1:
The patent changes the physical-chemical parameters of the binder by using a dual-binder system where one binder remains stable at low temperatures while the other provides high-temperature stability. This resolves the contradiction by ensuring the mounting mat maintains holding force across the entire temperature range from ambient to 1200°C without the organic binder liquefaction problem that occurs in conventional single-binder systems.
Solution Approach 2:
The patent employs a composite binder system combining two different binder materials with complementary properties. The first binder (e.g., polyvinyl alcohol or carboxymethyl cellulose) provides stability at low temperatures, while the second binder (e.g., alumina sol or silica sol) provides stability at high temperatures. This composite approach resolves the contradiction by ensuring consistent holding force across all operating temperatures.
2Temperature
If the mounting mat is designed to provide robust holding pressure at high temperatures, then thermal stability is improved, but the mat thickness and shear strength are significantly reduced due to binder burnout and material degradation
Solution Approach 1:
The patent uses inorganic binders (alumina sol, silica sol) that do not undergo organic decomposition and burnout like conventional organic binders. These inorganic binders maintain their binding properties and structural integrity at high temperatures up to 1200°C, preventing the thickness reduction and material degradation that occur with organic binder systems. The parameter change from organic to inorganic binder chemistry resolves the contradiction between thermal stability and mat thickness preservation.
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 proposed mounting mat provides improved holding performance and resistance to shear damage at low temperatures, ensuring the structural integrity and efficiency of exhaust gas treatment devices across varying temperature conditions.
Implementation Method 1
The mounting mat includes at least one ply or sheet that is comprised of heat resistant inorganic fibers, organic binder, and a colloidal inorganic oxide
Implementation Method 2
the organic binders become softer, characterized by a reduction in viscosity, such that the organic binders may be at least partially flowable
Implementation Method 3
heat resistant inorganic fibers
Implementation Method 4
The mounting mat also compensates for the fact that the metal housing expands more or less than the substrate itself
Data Source
AI summary
A mounting mat for an exhaust gas treatment device including high temperature resistant ceramic fibers containing alumina and/or high temperature resistant biosoluble inorganic fibers, organic binder which at least partially liquefies at elevated temperature prior to binder burnout, colloidal inorganic oxide and optionally intumescent material. The exhaust gas treatment device includes a housing, a fragile catalyst support structure resiliently mounted within the housing, and the mounting mat disposed in a gap between the housing and the fragile catalyst support structure.