Segmented Catalytic Converter for Rapid Light-Off and Noble Metal Reduction
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Solution Overview
Problem
Conventional catalytic converters face challenges in reducing emission levels, particularly in reaching light-off temperature quickly, leading to increased catalyst activation time and reduced emissions reduction performance, especially in turbocharged gasoline direct injection engines, which results in excessive emissions and noble metal consumption.
Innovation Solution
The improved catalytic converter design features two catalyst substrates with different diameters and volumes, separated inside the housing, forming a mixing region with varying noble metal content zones, and an oxygen sensor for real-time lambda control, allowing for efficient emissions reduction and reduced noble metal usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If the catalyst is mounted as close to the engine as possible to reduce activation time, then the catalyst activation time is reduced, but the catalyst is exposed to high temperature exhaust gas that can damage it
Solution Approach 1:
The catalytic converter is divided into multiple catalyst substrates (first, second, and third substrates) with different volumes and noble metal contents arranged in sequence along the exhaust flow path. The first substrate has smaller volume and higher noble metal content for rapid light-off, while subsequent substrates have larger volumes for sustained performance, segmenting the functional requirements to resolve both activation time and durability needs.
Solution Approach 2:
Different zones within the catalyst substrate have different noble metal contents, with the first substrate having higher noble metal content than subsequent substrates. This local quality variation allows the upstream catalyst to rapidly reach light-off temperature and protect downstream substrates from thermal damage, while maintaining overall system durability.
2Temperature
If the air-fuel ratio is enriched in high-speed high-load condition to reduce cylinder temperature, then the heat capacity of mixer is increased, but the emissions reduction performance of catalyst is degraded
Solution Approach 1:
The first catalyst substrate with higher noble metal content is positioned upstream to perform preliminary emissions reduction of hydrocarbons and carbon monoxide before the exhaust reaches subsequent substrates. This preliminary action ensures that even when rich air-fuel ratio exhaust degrades downstream catalyst performance, the initial emissions reduction has already occurred.
Solution Approach 2:
The system dynamically adapts to varying exhaust conditions by using multiple catalyst substrates with different characteristics. Under rich air-fuel ratio conditions, the first substrate with higher noble metal content provides robust emissions reduction, while under stoichiometric conditions, the entire multi-substrate system operates optimally, providing dynamic response to changing engine operating conditions.
3Device complexity
If a single integrated catalytic converter is used, then the device complexity is reduced, but the emissions reduction performance is insufficient for stringent standards
Solution Approach 1:
The catalytic converter employs multiple catalyst substrates (first, second, and third substrates) with different volumes and noble metal contents arranged in sequence, segmenting the emissions reduction function to achieve superior performance for meeting stringent ULEV II and SULEV standards while maintaining a relatively simple integrated housing structure.
Solution Approach 2:
The catalytic converter uses composite construction with multiple catalyst substrates having different noble metal contents and volumes, creating a composite catalytic system that combines the advantages of different catalyst configurations to achieve both high emissions reduction performance and cost-effectiveness.
4Reliability
If noble metal is used to reduce catalyst activation time in turbocharged GDI engine, then the emissions reduction performance is improved, but the cost and noble metal consumption are increased
Solution Approach 1:
The first catalyst substrate has higher noble metal content than the second and third substrates, concentrating noble metals where they are most needed for rapid light-off and initial emissions reduction. This local quality optimization reduces overall noble metal consumption while maintaining emissions reduction performance.
Solution Approach 2:
The catalytic converter segments noble metal distribution across multiple substrates, with the first substrate having higher noble metal content for rapid activation and subsequent substrates having lower content for sustained performance. This segmentation reduces total noble metal consumption compared to uniform distribution while maintaining emissions reduction performance.
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 design significantly reduces the time to reach light-off temperature, enhances emissions reduction performance, and decreases the amount of noble metal required, thereby improving efficiency and reducing costs while meeting stringent emission standards.
Implementation Method 1
a catalyst substrate mounted inside the housing. The surface of catalyst substrate may be coated with a noble metal and a washcoat
Implementation Method 2
the catalytic converter requires an activation temperature of approximatively 350° C. or more to start processing and emissions reduction of exhaust gas
Data Source
AI summary
The present disclosure relates to an improved catalytic converter capable of significantly reducing emissions by reducing the activation time of a catalytic device thereby improving emissions reduction performance, and an exhaust emission emissions reduction control method using the improved catalytic converter. The improved catalytic converter includes: a housing and two or more catalyst substrates disposed inside the housing, wherein the two or more catalyst substrates are separated inside the housing along a longitudinal direction, and the two or more catalyst substrates have a different diameter and a different volume.