Engine Exhaust Bypass Valve for Catalyst Oxygen Prevention
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Solution Overview
Problem
The purification efficiency of catalysts in exhaust gas purification systems deteriorates when oxygen is intercalated during a fuel-cut condition, leading to the potential discharge of noxious exhaust gases, as existing methods like catalyst purge are ineffective in maintaining efficiency until oxygen is purged.
Innovation Solution
An engine system with a bypass line and valve configuration that diverts exhaust gas around the exhaust gas purification apparatus during a fuel-cut condition, preventing oxygen intercalation and maintaining catalyst efficiency by routing exhaust gas through a bypass line or EGR line, thereby avoiding the catalyst when the vehicle is coasting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If fuel is injected richer than stoichiometric air-fuel ratio to purge oxygen from catalyst, then oxygen intercalation is removed, but purification efficiency remains deteriorated until oxygen is completely purged and noxious exhaust gas is discharged
Solution Approach 1:
The bypass valve opens in advance during fuel-cut conditions to prevent oxygen from entering the catalyst in the first place, rather than attempting to remove oxygen after it has already intercalated. This preliminary prevention action maintains catalyst efficiency continuously without the delayed response of traditional purge methods.
Solution Approach 2:
The system extracts oxygen from the exhaust gas path by routing exhaust through a bypass line that avoids the catalyst during fuel-cut conditions. This separation removes the harmful oxygen before it can intercalate into the catalyst, preventing efficiency deterioration.
2Reliability
If exhaust gas is routed through the exhaust gas purification apparatus during fuel-cut condition, then catalyst purification function is maintained, but oxygen intercalates in the catalyst causing efficiency deterioration
Solution Approach 1:
The system dynamically switches the exhaust gas flow path based on operating conditions. The bypass valve opens during fuel-cut conditions and closes during normal operation, allowing the system to adapt its configuration to prevent oxygen intercalation when needed while maintaining normal purification function when not needed.
Solution Approach 2:
The exhaust system is segmented into two separate paths: one through the catalyst for normal operation and another bypass path for fuel-cut conditions. This segmentation allows independent control of oxygen exposure to the catalyst by selecting which path the exhaust gas takes.
3Reliability
If bypass valve is opened during fuel-cut condition, then oxygen intercalation is prevented, but additional valve and control system are required
Solution Approach 1:
The bypass valve serves multiple functions: it prevents oxygen intercalation during fuel-cut conditions, enables exhaust gas recirculation pathways, and works coordination with the EGR system. This multi-functionality justifies the added component by providing multiple benefits from a single element.
Data Source
AI summary
An engine system includes: an engine including a plurality of combustion chambers generating driving torque by combustion of fuel; an exhaust gas purification apparatus installed at an exhaust line in which exhaust gas exhausted from the combustion chambers flows; a bypass line branched from the exhaust line at an upstream side of the exhaust gas purification apparatus and joining the exhaust line at a downstream side of the exhaust gas purification apparatus so that the exhaust gas flowing in the exhaust line bypasses the exhaust gas purification apparatus; and a bypass valve installed at the bypass line.