Honeycomb Structure with Varying Cell Sections
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Solution Overview
Problem
Conventional honeycomb structures experience high pressure loss, circumferential cracks, and thermal shock due to particulate matter deposition and thermal expansion issues, especially when used as filters for diesel engine exhaust gas, leading to reduced filtration efficiency and structural integrity.
Innovation Solution
A tubular honeycomb structure with varying cell section areas along its length, where cell sections are approximately equal at the center and gradually increase or decrease at the ends, reducing pressure loss and preventing circumferential cracks by optimizing cell density and thermal expansion management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the cell section area is kept constant over the entire length of the honeycomb structure, then the manufacturing process is simple and the structure is easy to produce, but the pressure loss increases due to fluid stagnation at the end faces
Solution Approach 1:
The patent applies local quality by making the cell section area different at different locations along the honeycomb structure. Specifically, the cell section area is made smaller at the end faces compared to the central portion, creating a non-uniform structure that reduces fluid stagnation and pressure loss at the inlet and outlet faces while maintaining ease of manufacture through controlled variation in cell dimensions.
2Reliability
If the cell density is increased to meet stricter exhaust gas regulations, then the purification efficiency is improved, but the pressure loss at the end faces increases sharply
Solution Approach 1:
The patent resolves this contradiction by implementing local quality through spatially varying cell section areas. The end faces have smaller cell sections that reduce fluid stagnation and associated pressure loss, while the central portion maintains higher cell density for effective purification. This allows the structure to achieve high purification efficiency without suffering from excessive pressure loss at the end faces.
3Stability of the object's composition
If the peripheral area of the end face is blocked by a retainer ring to prevent positional shift, then the structural stability is improved, but the pressure loss increases due to blocked cell passages
Solution Approach 1:
The patent addresses this contradiction by making the cell section area smaller at the end faces where the retainer ring is located. This local reduction in cell section area compensates for the flow restriction caused by the retainer ring, maintaining adequate flow capacity while preserving the structural stability provided by the retainer ring for preventing positional shift.
4Ease of manufacture
If the outer diameter is kept constant over the entire length, then the manufacturing process is simple and cost-effective, but the pressure loss and thermal stress distribution are suboptimal
Solution Approach 1:
The patent implements local quality by varying the outer diameter along the length of the honeycomb structure. The outer diameter is made smaller at the end faces and larger in the central portion, creating a non-uniform profile that reduces pressure loss at the end faces while maintaining ease of manufacture through controlled dimensional variation that can be achieved with standard manufacturing processes.
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 lower pressure loss and enhanced structural integrity by allowing smoother fluid flow and reducing thermal stress, thereby improving filtration efficiency and preventing damage from particulate matter deposition and thermal shock.
Implementation Method 1
there is placed, on at least one end face of the honeycomb formed body, a setter made of a material having a contraction coefficient of firing different from that of the honeycomb formed body and, in this state, the honeycomb formed body is fired to give rise to deformation in such a way that the areas of the sections of the individual cells (cell sections), normal to the flow direction of fluid, increase gradually or decrease gradually at each cell end at the setter-placed end face
Data Source
AI summary
A tubular honeycomb structure 1 comprising partition walls 2 which define and form a plurality of cells 3 each functioning as a fluid passage extending from one end face 4 of honeycomb structure to other end face 5, wherein the areas of the sections of the individual cells 3 (cell sections) normal to the flow direction A of fluid are so made as to be approximately equal to each other over a given range of the center of each cell and its vicinity in the fluid flow direction A and to gradually decrease or gradually increase at each cell end of at least one end face 4 of honeycomb structure in the fluid flow direction A. This honeycomb structure can reduce the incoming loss and outgoing loss of a fluid such as exhaust gas or the like and can show a lower pressure loss.