Conductive Honeycomb Structure for Uniform Catalyst Heating
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Solution Overview
Problem
In low voltage HEVs, the existing electric heating catalyst (EHC) systems face challenges in achieving uniform temperature distribution within the conductive honeycomb structure during simultaneous energization, leading to inefficient catalyst activation and exhaust gas purification performance.
Innovation Solution
A conductive honeycomb structure with specifically designed electrode layers and configurations, including varying electric resistances and distances between electrode layers, is implemented to enhance heat generation preferentially near the inlet, ensuring uniform temperature distribution and catalyst activation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a heater is disposed on the upstream side of the catalyst honeycomb structure, then the catalyst temperature can be increased, but temperature distribution becomes non-uniform along the flow direction causing delayed temperature increase in distant catalyst regions
Solution Approach 1:
The heater is divided into multiple heating sections corresponding to different axial regions of the honeycomb structure. Each heating section independently heats a specific region, transforming a single centralized heating source into distributed heating zones that collectively achieve uniform temperature distribution throughout the catalyst structure.
Solution Approach 2:
Different heating sections are positioned at specific locations (front, middle, rear) of the honeycomb structure to provide localized heating where needed. This ensures that each region of the catalyst receives appropriate heat input, preventing temperature gradients and achieving uniform activation across the entire catalyst volume.
2Productivity
If the EHC is electrified simultaneously with engine starting in low voltage HEVs, then exhaust gas purification can begin earlier, but temperature distribution uniformity deteriorates making it impossible for entire catalyst to reach activation temperature efficiently
Solution Approach 1:
The heating system is segmented into multiple independently controllable heating sections that can be activated simultaneously or sequentially. This segmentation allows the system to maintain uniform temperature distribution even during simultaneous energization by coordinating the operation of individual heating sections to compensate for heat loss at the inlet.
Solution Approach 2:
The multiple heating sections operate continuously and cooperatively to maintain uniform heating throughout the catalyst structure during simultaneous energization. This continuous coordinated action ensures that the entire catalyst reaches activation temperature uniformly, enabling immediate exhaust gas purification without temperature distribution issues.
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
The enhanced temperature uniformity improves catalyst utilization and exhaust gas purification performance in low voltage HEVs by ensuring the catalyst reaches activation temperature efficiently during simultaneous energization.
Implementation Method 1
an electric resistance heating body (conductive honeycomb structure) having a honeycomb structure
Data Source
AI summary
A conductive honeycomb structure that is divided into four equal portions in a flow path direction of cells in the structure to form four regions of A, B, C, and D from a side closer to a first end face, and an average value of electric resistances measured between two points in each of the four regions is represented as RA, RB, RC, and RD in this order from the side closer to the first end face. A relational expression of RA≤RB≤RC≤RD (excluding RA=RB=RC=RD) is satisfied provided that the two points being determined so that a distance between a pair of electrode layers arranged on an outer peripheral side wall of the structure is the longest in the cross section perpendicular to the flow path direction of the cells.