Honeycomb Structure with Monolithic Supporting Bulge
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Solution Overview
Problem
Honeycomb structures used in gasoline engines face insufficient thermal shock resistance due to differences in thermal expansion ratios between the honeycomb structure and circumferential coating materials, and they are prone to shifting during high-temperature exhaust gas exposure, which complicates their use as exhaust gas purifying filters.
Innovation Solution
A honeycomb structure with porous partition walls and a porous outer wall, featuring a supporting bulge with protruding support portions and beam portions, all formed monolithically from ceramic material, which enhances thermal shock resistance and prevents shifting by eliminating the need for high holding pressures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If the thickness of partition walls is decreased or porosity is increased to reduce weight and improve catalyst activation speed, then the honeycomb structure becomes more susceptible to damage from holding pressure during canning, but this compromises structural strength
Solution Approach 1:
The invention applies preliminary action by forming a circumferential coating material on the outer wall before the honeycomb structure is subjected to holding pressure during canning. This coating layer is specifically designed to prevent damage from compression forces, allowing the underlying honeycomb structure to have reduced partition wall thickness and higher porosity without compromising structural integrity during the canning process
Solution Approach 2:
The invention employs composite materials by combining the honeycomb substrate (made from ceramic particles and binder) with a circumferential coating material applied to the outer wall. This composite structure provides the inner honeycomb with high porosity and low weight while the outer coating layer provides enhanced mechanical strength and resistance to holding pressure, resolving the contradiction between lightweight design and structural strength
2Strength
If holding pressure is decreased to avoid damaging the honeycomb structure, then the honeycomb structure shifts from the predetermined received position when exhaust gas pressure or vibration is applied
Solution Approach 1:
The circumferential coating material is applied in advance to the outer wall of the honeycomb structure before canning. This pre-applied coating layer increases the friction between the honeycomb structure and the can member, providing sufficient grip to prevent shifting under exhaust gas pressure or vibration without requiring high holding pressure that would damage the structure
Solution Approach 2:
The circumferential coating material acts as an intermediary between the honeycomb structure and the can member. It provides a surface that enhances adhesion and friction, mediating the interaction between the honeycomb structure and the can member to prevent shifting while allowing the use of lower holding pressures that would not damage the honeycomb structure
3Reliability
If a circumferential coating material is used on the outer wall to prevent shifting, then thermal stress is generated at the boundary between the honeycomb structure and coating material during high-temperature exposure, reducing thermal shock resistance
Solution Approach 1:
The invention applies parameter changes by carefully controlling the thermal expansion coefficient of the circumferential coating material to match that of the honeycomb substrate. This parameter matching reduces thermal stress generation during high-temperature exposure, allowing the coating to provide shifting prevention without compromising thermal shock resistance
Solution Approach 2:
The circumferential coating material is formulated as a composite with specific properties including a thermal expansion coefficient matched to the honeycomb substrate. This composite coating provides both mechanical adhesion for preventing shifts and thermal compatibility for maintaining thermal shock resistance under high-temperature exhaust gas exposure
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 honeycomb structure achieves high thermal shock resistance, low pressure loss, and rapid catalyst activation, while maintaining structural integrity and preventing movement during high-temperature exposure, thus addressing the issues of thermal expansion and shifting.
Implementation Method 1
porous partition walls defining and forming a plurality of cells which extend from an inflow end face to an outflow end face
Implementation Method 2
the partition walls and the outer wall of the honeycomb structure body and the support portions and the side wall portion of the supporting bulge are all formed monolithically by formation of a ceramic raw material
Data Source
AI summary
A honeycomb structure includes a pillar-shaped honeycomb structure body including porous partition walls defining and forming a plurality of cells which extend from an inflow end face to an outflow end face, and a porous outer wall surrounding the partition walls, a porous supporting bulge disposed to extend out from a circumference of the outer wall so that at least a part of the outer wall is exposed, and plugging portions arranged in open ends of the cells, and the supporting bulge has support portions and a side wall portion, and the partition walls and the outer wall of the honeycomb structure body and the support portions and the side wall portion of the supporting bulge are all formed monolithically by formation of a ceramic raw material.