Oblique Wire Catalyst Structure for Exhaust Gas Purification
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Solution Overview
Problem
The existing catalyst structures in internal combustion engine exhaust passages experience increased flow passage resistance due to repeated compression and expansion of exhaust gas, which reduces the purification efficiency.
Innovation Solution
A catalyst structure is designed with wire-shaped members arranged obliquely to the exhaust gas flow direction, reducing cross-sectional area changes and pressure loss, while increasing the surface area for gas-catalyst contact, and varying density along the flow direction to enhance purification efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If wire-shaped members are arranged orthogonal to the exhaust gas flow direction to form a mesh base member, then the surface area is increased and the purification rate is improved, but the flow passage resistance is increased due to repeated compression and expansion of exhaust gas
Solution Approach 1:
The patent applies asymmetry by arranging wire-shaped members obliquely rather than orthogonally to the exhaust gas flow direction. This asymmetric arrangement prevents the repeated compression and expansion of exhaust gas that occurs with orthogonal arrangements, thereby reducing flow passage resistance while maintaining adequate surface area for catalytic reaction.
Solution Approach 2:
The patent changes the arrangement parameter of wire-shaped members from orthogonal to oblique relative to the exhaust gas flow direction. This parameter change fundamentally alters the flow dynamics, eliminating the compression-expansion cycle and reducing pressure loss, while the mesh structure still provides sufficient surface area for high purification rates.
2Productivity
If the cross-sectional area of the base member is greatly changed in the flow direction to increase surface area, then the purification efficiency is improved, but the pressure loss is increased due to expansion and compression of exhaust gas
Solution Approach 1:
By using oblique arrangement of wire-shaped members, the patent creates an asymmetric structure that maintains relatively constant cross-sectional area in the flow direction, preventing the pressure fluctuations that would otherwise occur with large area changes.
Solution Approach 2:
The patent shifts the surface area increase strategy from the flow direction (cross-sectional area changes) to a three-dimensional mesh structure with oblique wires, utilizing spatial arrangement in multiple dimensions to provide surface area without compromising flow characteristics.
Data Source
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AI summary
A catalyst structure, which makes it possible to reduce the flow passage resistance and raise the purification rate, is provided. A catalyst structure provided in an exhaust passage of an internal combustion engine comprises a base member which is formed by combining wire-shaped members, wherein the wire-shaped members do not include any wire-shaped member which is arranged to be orthogonal to a flow direction of an exhaust gas, and the wire-shaped members include wire-shaped members which are arranged obliquely with respect to the flow direction of the exhaust gas. The change in the cross-sectional area of the base member is suppressed by arranging the wire-shaped members obliquely with respect to the flow direction of the exhaust gas.