Metallic Honeycomb Catalyst Substrate Hole Layout for Cold-Start Purification
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Solution Overview
Problem
Existing catalyst carrying substrates face a trade-off between high pressure loss and purification performance, especially during cold starts, due to turbulent flows generated by perforated metallic foils, which degrade engine output and fuel efficiency.
Innovation Solution
A catalyst carrying substrate with a specific arrangement of holes in the metallic foils, defined by the ratio of h/p > 1.0, where h is the arrangement interval in the z-direction and p in the θ-direction, reduces pressure loss while maintaining high purification performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the flow rate of the exhaust gas is high, then the purification performance is improved, but the pressure loss becomes higher due to turbulent flows
Solution Approach 1:
The patent applies local quality by creating different flow conditions in different regions of the catalyst carrier. The inner peripheral area (near the center axis) generates turbulent flows for enhanced mass transfer and purification, while the outer peripheral area maintains laminar flows to minimize pressure loss. This spatial differentiation of flow characteristics allows simultaneous optimization of both purification performance and pressure loss reduction.
Solution Approach 2:
The patent introduces a radial dimension to the flow pattern by creating swirl flows that rotate around the center axis. This dimensional change from simple axial flow to rotational-swirl flow enables the generation of turbulent eddies in the inner region while controlling overall pressure drop through the structured rotation pattern.
2Productivity
If turbulent flows are generated to promote mass transfer, then purification performance is improved, but pressure loss increases resulting in decrease in engine output
Solution Approach 1:
The patent applies local quality by creating different flow conditions in different regions of the catalyst carrier. The inner peripheral area (near the center axis) generates turbulent flows for enhanced mass transfer and purification, while the outer peripheral area maintains laminar flows to minimize pressure loss. This spatial differentiation of flow characteristics allows simultaneous optimization of both purification performance and pressure loss reduction.
Solution Approach 2:
The patent applies partial action by generating turbulent flows only in the inner peripheral area rather than throughout the entire catalyst carrier. This partial turbulence generation provides sufficient mass transfer enhancement for improved purification while limiting the overall pressure loss increase, thereby maintaining engine output.
3Loss of time
If the heat capacity of the catalyst carrier is reduced for quick catalyst activation, then emissions at cold start are suppressed, but the structural integrity and durability may be compromised
Solution Approach 1:
The patent segments the catalyst carrier structure into a thin-walled honeycomb body and a separate outer mantle. This segmentation allows the inner honeycomb structure to have minimal wall thickness for low heat capacity and quick activation, while the outer mantle provides additional structural support and durability without significantly increasing the overall heat capacity.
Solution Approach 2:
The patent employs thin-walled metallic foils to construct the honeycomb body, using flexible thin film structures that minimize thermal mass while maintaining structural integrity through the corrugated geometry and support from the outer mantle.
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 substrate achieves both low pressure loss and high purification performance by optimizing hole arrangement, particularly at cold starts, thereby enhancing engine output and fuel efficiency.
Implementation Method 1
turbulent flows are generated in a hole area. The turbulent flows are significantly effective in promotion of a mass transfer of the gas
Implementation Method 2
there has been a need for a technology to reduce the heat capacity of a catalyst carrying substrate because of a need for quickly activating a catalyst to suppress emissions of harmful substances at the time of a cold start
Data Source
Figure 1
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Figure 3b~3c
AI summary
[Problem] Provided is a catalyst carrying substrate that achieves both the suppression of an increase in pressure loss and an improvement in purification performance during a cold start. [Solution] The present invention is characterized in that in a catalyst carrying substrate that is obtained by at least partially joining a honeycomb body, obtained by winding or laminating a metal flat foil and a metal wave foil, and an outer mantle surrounding the outer circumferential surface of the honeycomb body, a plurality of thickness direction through-holes are formed in the flat foil and the wave foil, the holes being spaced apart from each other without being continuous to each other, and the plurality of holes satisfy the following conditional expression (1). h/p>1.0 Here, h is the disposition interval of the holes in the axial direction of the honeycomb body, p is a disposition interval of the holes in a direction perpendicular to the axial direction and along the foils.