Porous Outer Wall Cell Structure for Fast Temperature Rise
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Solution Overview
Problem
Existing cell structures face challenges in achieving a rapid temperature rise rate and uniform temperature distribution, which affects catalytic activity and mechanical strength, especially in large-sized vehicles and diesel engine exhaust gas purification systems.
Innovation Solution
A cell structure with a porous outer wall portion having a porosity of 40% or more, comprising a honeycomb or foam-shaped structure with an inside shell layer of higher porosity and an outside shell layer of lower porosity, and a method involving a coating material with a pore former to enhance heat-insulating properties and mechanical strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the thickness of cell partition walls is thinned or porosity is increased to reduce heat capacity, then the temperature rise rate is improved, but mechanical strength deteriorates
Solution Approach 1:
The invention applies different porosity characteristics to different regions of the outer wall portion. The inner peripheral portion has higher porosity (40-70%) to reduce heat capacity and improve temperature rise rate, while the outer peripheral portion has lower porosity (10-40%) to provide mechanical strength and prevent deformation during extrusion forming. This local differentiation resolves the contradiction between temperature rise rate and mechanical strength.
2Strength
If a shell layer is formed by coating the outer peripheral portion with ceramic cement to improve mechanical strength, then mechanical strength is improved, but heat capacity increases and temperature rise rate is lowered
Solution Approach 1:
The invention uses a porous outer wall portion with controlled porosity (10-70%) instead of a dense ceramic cement coating. The porous structure provides mechanical strength while maintaining low heat capacity, allowing the cell structure to achieve both improved strength and fast temperature rise rate without the trade-off inherent in dense coating methods.
3Reliability
If a coating layer is provided on the outer peripheral surface to improve canning resistance, then canning resistance is improved, but heat capacity of the outer wall portion increases and heat transfer to the outer wall side occurs
Solution Approach 1:
The invention differentiates the outer wall portion into inner and outer peripheral portions with different porosity characteristics. The inner peripheral portion (higher porosity) faces the cell structural portion and provides heat insulation to improve temperature rise rate, while the outer peripheral portion (lower porosity) faces the external environment and provides canning resistance. This local quality differentiation resolves the contradiction between canning resistance and temperature rise rate.
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 enables a faster temperature rise rate and more uniform temperature distribution within the cell structure, improving catalytic activity and mechanical strength while maintaining heat-insulating properties, thus effectively addressing the issues of temperature uniformity and mechanical strength.
Implementation Method 1
the outer wall portion has at least a porous layer having a porosity of 40% or more
Data Source
AI summary
There is provided a cell structure, where the outer wall portion has high heat-insulating ability, the cell structural portion has a high temperature rise rate, and a temperature distribution is more uniform, and a method for manufacturing the cell structure. The cell structure 1 includes: a cell structural portion 4 having partition walls forming a plurality of cells extending from one end face to the other end face, and an outer wall portion 5 disposed on an outer peripheral surface of the cell structural portion 4. The outer wall portion 5 has at least a porous layer having a porosity of 40% or more or a porous layer having a hollow body. The manufacturing method can easily manufacture the cell structure.