Honeycomb Structure Pressure Loss Control
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Solution Overview
Problem
Conventional honeycomb structures for filtering exhaust gas face challenges in achieving precise pressure loss control and ash deposition capacity, leading to increased fuel consumption and reduced productivity due to fluctuations in pressure loss values.
Innovation Solution
A honeycomb structure with a controlled number of unfired second plugging portions, specifically within 3% of the cell open ends, allows for fine adjustment of pressure loss and improved productivity by reducing out-of-specification products and ash deposition, while maintaining ash deposition capacity and engine output.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the number of second plugging portions is increased to adjust pressure loss, then pressure loss control precision is improved, but ash deposition allowable capacity is reduced
Solution Approach 1:
The patent applies local quality by differentiating between two types of plugging portions: first plugging portions (fired) and second plugging portions (unfired). The second plugging portions are strategically placed only in circumferential cells (outermost 3 rows) rather than uniformly throughout, creating localized control zones. This allows pressure loss adjustment in specific regions without compromising the overall ash deposition capacity of the filter medium, as the unfired plugging portions in circumferential cells do not significantly reduce the effective filtration area while still achieving the desired pressure loss characteristics.
Solution Approach 2:
The patent utilizes parameter changes by controlling the firing state of plugging portions - first plugging portions are fired (calcined at high temperature) while second plugging portions remain unfired. This parameter change (fired vs. unfired state) creates different flow resistance characteristics, enabling precise pressure loss adjustment. The unfired second plugging portions provide adjustable resistance without the structural changes associated with firing, allowing fine-tuning of pressure loss while preserving ash deposition capacity.
2Reliability
If pressure loss fluctuation is large, then regeneration interval should be shortened to maintain performance, but this increases fuel consumption
Solution Approach 1:
The patent applies preliminary action by adjusting the pressure loss characteristics during the manufacturing stage through strategic placement of second plugging portions in circumferential cells. By pre-configuring the pressure loss to match the target value within ±3% tolerance, the filter is optimized for extended regeneration intervals from the outset. This preliminary optimization eliminates the need for frequent regeneration operations, thereby reducing cumulative fuel consumption without compromising performance stability.
Solution Approach 2:
The patent replaces mechanical/structural adjustments (changing filter geometry or material properties) with a chemical/placing-based solution: strategically positioning unfired plugging portions during manufacturing. This substitution allows precise pressure loss control through placement configuration rather than structural modification, enabling optimized regeneration intervals and reduced fuel consumption.
3Stability of the object's composition
If second plugging portions are placed at outermost circumference cells to prevent PM disproportion deposition, then PM distribution is improved, but pressure loss adjustment precision is reduced
Solution Approach 1:
The patent applies local quality by restricting second plugging portions to only the circumferential cells (outermost 3 rows) rather than distributing them uniformly across all cells. This localized placement achieves two objectives simultaneously: it prevents excessive PM deposition at the circumferential region (improving PM distribution stability) while providing sufficient degrees of freedom for pressure loss adjustment. The concentrated placement in circumferential cells creates a controlled gradient that balances both PM distribution and pressure loss characteristics.
Solution Approach 2:
The patent utilizes parameter changes by varying the placement density and position of second plugging portions within the circumferential region. By adjusting which specific circumferential cells receive unfired plugging portions, the manufacturer can fine-tune the pressure loss parameter while maintaining the beneficial PM distribution effect. This parameter optimization enables achieving both PM distribution stability and pressure loss precision within the same configuration.
Data Source
Figure 1
Figure 2
Figure 3~4A
AI summary
Provided is a honeycomb structure 1 including a honeycomb structure body 6, first plugging portions 8, and second plugging portions 9. The honeycomb structure body 6 has a porous partition wall 4. The first plugging portions 8 are disposed at an outflow side end face 2b of inlet cells 3a and an inflow side end face 2a of outlet cells 3b. The inlet cells 3a are the predetermined cells 3 of the honeycomb structure body 6. The outlet cells 3b are the residual cells 3 of the honeycomb structure body. The second plugging portions 9 are not fired. The first plugging portions 8 form a checkered pattern at the inflow side end face 2a and the outflow side end face 2b. The number of the second plugging portions 9 is within 3% of the number of cell open ends where the first plugging portions 8 are not formed, on both end faces 2a and 2b of the honeycomb structure body 6.