Engine Exhaust Catalyst Offset Pipe Uniform Flow
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Solution Overview
Problem
In conventional engine exhaust devices, the overlapping configuration of catalysts leads to uneven exhaust gas flow, inefficient use of catalysts, increased ventilation resistance, and decreased engine output due to uneven flow rates.
Innovation Solution
The exhaust gas outlet pipe of the downstream catalyst is offset towards the overlap with the upstream catalyst, and the EGR outlet is positioned away from the exhaust gas outlet pipe to equalize the flow, with the exhaust gas outlet pipe disposed below the center axis of the catalysts and having a dihedral angle between 60° and 120° to enhance gas flow and moisture collection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If catalysts are disposed in overlapping configuration to reduce device size, then the area occupied by exhaust device is reduced, but exhaust gas flow becomes uneven and ventilation resistance increases
Solution Approach 1:
The patent applies local quality by creating a through-hole in the downstream catalyst at a position offset from the catalyst center, specifically at a location that corresponds to the upstream catalyst region. This localized structural modification redirects exhaust gas flow to pass through the overlapping region, ensuring uniform distribution and reducing ventilation resistance while maintaining the compact overlapping configuration.
2Area of stationary object
If catalysts are disposed in overlapping configuration to reduce device size, then the area occupied by exhaust device is reduced, but catalyst usage efficiency decreases
Solution Approach 1:
The through-hole is strategically positioned in the downstream catalyst at an offset location corresponding to the upstream catalyst region. This ensures that exhaust gas flows through the overlapping area where the upstream catalyst is located, maximizing contact between exhaust gas and catalyst surface in the overlapping region, thereby improving catalyst usage efficiency while maintaining compact device size.
3Device complexity
If exhaust gas outlet pipe is positioned at catalyst center, then flow path is simple, but exhaust gas flow distribution becomes uneven
Solution Approach 1:
The patent employs asymmetry by positioning the exhaust gas outlet pipe at an offset location from the catalyst center, rather than at the center. This asymmetric positioning creates a flow path that passes through the overlapping region with the upstream catalyst, ensuring uniform exhaust gas distribution across the catalyst surface while maintaining a relatively simple overall flow path structure.
Data Source
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AI summary
An engine exhaust device includes: a first catalyst disposed in an exhaust passage of an engine, and purifying exhaust gas discharged from the engine; a second catalyst disposed downstream of the first catalyst in a direction of a flow of the exhaust gas, and purifying the exhaust gas that has passed through the first catalyst; a connection member having a tubular shape, forming a part of the exhaust passage, and connecting the first catalyst and the second catalyst together; and an exhaust gas outlet pipe disposed downstream of the second catalyst in the flow of the exhaust gas, and allowing the exhaust gas that has passed through the second catalyst to flow in a downstream area of the exhaust passage. The first catalyst has a downstream end face and the second catalyst has an upstream end face. The downstream end face and the upstream end face form a predetermined dihedral angle. The upstream end face of the second catalyst and a side surface of the first catalyst closely face each other to form an overlap. A center axis of the exhaust gas outlet pipe is offset further toward the first catalyst than a center axis of the second catalyst is.