Electric Heated Catalyst With Non-Uniform Cellular Structure
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Solution Overview
Problem
Conventional electric heated catalyst (eCAT) systems face inefficiencies in exhaust gas flow and temperature distribution, leading to suboptimal catalytic converter performance during engine cold starts, particularly due to non-uniform heat generation and gas flow characteristics in different exhaust system configurations.
Innovation Solution
A multi-sectional, multi-regional electric heater with a cellular structure that varies in density and porosity to redirect and evenly distribute exhaust gas flow, ensuring uniform temperature distribution across the heater and catalyst, using smaller gas passages with larger surface areas in certain regions to compensate for flow characteristics in angled, turbocharged, and non-turbo systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a conventional electric heater with uniform cellular structure is used, then the heater structure is simple and easy to manufacture, but the exhaust gas flow is non-uniform and temperature distribution is non-uniform across the catalyst
Solution Approach 1:
The heater employs a non-uniform cellular structure where different regions have different cell densities and passage sizes. Specifically, the heater includes a first region with a first cellular structure and a second region with a second cellular structure, where the cell passages in the second region are smaller than those in the first region. This local variation in structural quality redirects exhaust gas flow to achieve uniform temperature distribution across the catalyst surface.
2Temperature
If the cellular structure is made more dense in certain areas to redirect flow, then temperature distribution becomes uniform, but the heater structure becomes more complex and difficult to manufacture
Solution Approach 1:
The heater is divided into multiple distinct regions, each with its own cellular structure characteristics. The heater includes a first region with a first cellular structure and a second region with a second cellular structure, creating segmented zones with different flow resistance properties. This segmentation allows independent optimization of each region's cell size and density to control overall exhaust gas distribution.
3Temperature
If exhaust gas flow is not uniformly distributed, then certain areas of the catalyst receive insufficient heat, but increasing flow restriction increases backpressure and reduces system efficiency
Solution Approach 1:
The heater modifies the physical parameters of the cellular structure, specifically varying the cell passage size and density across different regions. The second region has smaller cell passages than the first region, creating a gradient in flow resistance parameters that redirects exhaust gas without causing excessive backpressure buildup.
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 approach enhances the efficiency of catalytic converters by achieving uniform temperature profiles across the catalyst, reducing the time to reach light-off temperature and preventing heater damage, thereby improving emissions conversion efficiency and extending system lifespan.
Implementation Method 1
an electric heater between the exhaust pipe and the catalyst
Implementation Method 2
an electric heater upstream of the catalyst and having a cellular structure that is more dense in certain areas than other areas such that flow of exhaust gas is restricted through the certain areas relative to the other areas and redirected through the other areas
Implementation Method 3
a catalyst in fluid communication with the exhaust pipe
Data Source
AI summary
An automotive exhaust system includes an exhaust pipe and a catalytic converter. The catalytic converter includes a catalyst in fluid communication with the exhaust pipe, and an electric heater between the exhaust pipe and the catalyst. The electric heater includes a cellular structure that defines a plurality of smaller and larger cells. The smaller cells occupy a contiguous half of the cellular structure.