Variable Cylinder Exhaust Catalyst Segmentation
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Solution Overview
Problem
Conventional exhaust systems for variable cylinder engines face challenges in maintaining exhaust gas purification performance without increasing the number of catalysts, leading to potential NOx production and inefficiencies in blow-by gas handling.
Innovation Solution
The system employs a main catalyst with a flattened cross-sectional shape to separate exhaust gas flows from activation and deactivation cylinder groups, using a sub-catalyst and partition walls to ensure independent gas flow paths, reducing the need for additional catalysts and optimizing the arrangement for minimal height and part count, while the intake system uses a partitioned air cleaner and blow-by gas returning pipe to direct blow-by gas only to the activation cylinder group for purification.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a sub-catalyst is added on the downstream side of the main catalyst to prevent NH3 oxidation back to NO, then the purification performance is improved, but the cost increases due to increased number of catalysts
Solution Approach 1:
The main catalyst is segmented into multiple cells arranged in parallel, with partition walls creating independent flow paths. This segmentation allows the system to maintain purification performance without needing additional catalyst components, as each cell functions independently to process exhaust gas and fresh air separately
Solution Approach 2:
The invention transitions from a single-stream catalyst design to a multi-cell parallel architecture, adding spatial dimensionality to the catalyst structure. This dimensional change enables independent flow paths within the same catalyst component, eliminating the need for additional downstream catalysts while maintaining purification effectiveness
2Device complexity
If exhaust pipes of activation and deactivation cylinders are gathered together before the main catalyst, then the structure is simplified, but temperature drop of the main catalyst occurs and purification performance is compromised
Solution Approach 1:
The exhaust system is segmented into separate paths: activation cylinder exhaust goes through the sub-catalyst while deactivation cylinder exhaust bypasses it. This segmentation prevents mixing of hot exhaust with cooler fresh air before the main catalyst, maintaining optimal temperature for catalyst operation without requiring complex insulation or heating systems
Solution Approach 2:
Different quality treatment is applied to different exhaust streams based on their temperature characteristics. Hot exhaust from activation cylinders receives sub-catalyst treatment, while cooler exhaust from deactivation cylinders bypasses the sub-catalyst. This local quality approach maintains overall system simplicity while preserving main catalyst temperature
3Device complexity
If blow-by gas is introduced into a single air cleaner for both activation and deactivation cylinder groups, then the structure is simplified, but unburnt blow-by gas may pass through deactivation cylinders and be emitted to atmosphere
Solution Approach 1:
The air cleaner is segmented with partition walls that create separate intake passages for activation and deactivation cylinder groups. This segmentation ensures blow-by gas is directed only to activation cylinders where combustion occurs, preventing unburnt emissions while maintaining a unified air cleaner structure
Solution Approach 2:
Partition walls act as intermediaries within the air cleaner to separate blow-by gas flow paths. These internal partitions guide blow-by gas exclusively to activation cylinders without requiring separate external air cleaners, thus preventing harmful emissions while preserving structural simplicity
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
This configuration maintains exhaust gas purification performance without increasing catalyst numbers, suppresses NOx production, and ensures effective blow-by gas purification with a simplified structure, minimizing changes to existing piping and extending maintenance cycles.
Implementation Method 1
a main catalyst disposed at the gathering section
Implementation Method 2
CO and H2 included in exhaust gas in the activation cylinders react in the pre-catalysts to produce H2
Implementation Method 3
gas passing therethrough is partitioned into flows independent of each other in a flow path direction
Data Source
AI summary
An exhaust system for a variable cylinder engine for assuring purification of exhaust gas without increasing the number of catalysts and an intake system for purifying blow-by gas. The exhaust system includes an activation side exhaust pipe connected to an activation cylinder group that operates normally. A deactivation side exhaust pipe is connected to a deactivation cylinder group wherein fuel supply is stopped under a particular condition. A gathering section is connected to downstream ends of the activation side exhaust pipe and the deactivation side exhaust pipe with a sub-catalyst disposed in the activation side exhaust pipe and a main catalyst disposed at the gathering section. The main catalyst is formed wherein gas passing therethrough is partitioned into flows independent of each other in a flow path direction. The activation side exhaust pipe and the deactivation side exhaust pipe are connected in a mutually independent state to the main catalyst.