Multiple Layer Mounting Mat for Exhaust Substrate Protection
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Solution Overview
Problem
Exhaust gas treatment devices face challenges in protecting fragile catalyst support structures from thermal and mechanical shocks due to their brittle nature, requiring effective insulation and mounting systems that maintain secure engagement forces across varying temperatures without adding weight or bulk.
Innovation Solution
A multiple layer mounting mat system comprising non-intumescent or intumescent sheets of inorganic fibers with a microporous insulating layer, providing thermal insulation and mechanical support by engaging the substrate and housing, while maintaining compressive forces to secure the substrate within the housing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a mounting mat is positioned between the substrate and housing to protect the fragile substrate, then the substrate is protected from thermal and mechanical shock, but the device weight and bulk increase
Solution Approach 1:
The patent employs a microporous ceramic coating layer applied to the substrate surface. This porous structure provides thermal insulation and mechanical protection while maintaining low weight, as the porous nature reduces material density compared to solid alternatives. The coating thickness can be optimized to provide adequate protection without excessive weight addition.
Solution Approach 2:
The patent uses a composite structure combining the fragile ceramic substrate with a more ductile metallic housing and a mounting mat system. This composite approach allows each material to contribute its strengths: the ceramic provides catalytic surface area, the metal provides mechanical strength and thermal mass, and the mounting mat provides thermal insulation and mechanical cushioning, achieving overall system optimization.
2Temperature
If a mounting mat is used to provide thermal insulation, then the housing operating temperature is reduced, but the engagement force between the mounting mat and substrate decreases at high temperatures
Solution Approach 1:
The patent utilizes the temperature-dependent properties of the mounting mat material, specifically its phase transition behavior. The mounting mat is designed to undergo a phase change at elevated temperatures that causes expansion or stiffening, thereby maintaining or increasing engagement force with the substrate precisely when thermal insulation is most needed to protect the housing.
Solution Approach 2:
The mounting mat material is selected to exhibit controlled thermal expansion characteristics that ensure maintained engagement force across the operating temperature range. The expansion properties are engineered so that as temperature increases, the mounting mat expands to fill gaps and maintain contact pressure with the substrate, counteracting the softening effect of heat.
Data Source
AI summary
A mat or mat-pre-form hybrid for use in an exhaust gas treatment device, such as catalytic converters and diesel particulate traps that are used in automotive exhaust systems. The mat or hybrid may be used as a mounting mat to mount a fragile monolith within an outer housing of an exhaust gas treatment device or as thermal insulation in an end cone of the exhaust gas treatment device.