SiC Electrically Heated Catalyst Device with Optimized Coat Amount
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Solution Overview
Problem
Conventional electrically heated catalyst devices (EHCs) exhibit insufficient heating properties and exhaust gas purification performance when the catalyst temperature is increased by electric heating, leading to suboptimal purification efficiency.
Innovation Solution
The EHC comprises a substrate with a SiC partition wall, an inflow side catalyst layer containing Pd, and an outflow side catalyst layer containing Rh, with the catalyst layers extending more than 50% of the substrate's length, optimizing the total coat amount between 138 g/L and 150 g/L to enhance heating and purification efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the total coat amount of catalyst layers is increased to improve exhaust gas purification performance, then the purification performance improves, but the heating property (warm-up property) by electric heating deteriorates
Solution Approach 1:
The patent optimizes the total coat amount parameter to a specific range (138-150 g/L) to balance two conflicting requirements: sufficient catalyst quantity for high purification performance and limited catalyst quantity for good heating property. By precisely controlling this parameter within a narrow optimal range, the invention resolves the contradiction between purification performance and heating efficiency.
2Reliability
If the catalyst layer thickness is increased to improve purification performance, then the purification performance improves, but the pressure loss increases
Solution Approach 1:
The patent controls the total coat amount within the optimal range of 138-150 g/L, which represents a precise parameter optimization to achieve sufficient purification performance while avoiding excessive pressure loss. This parameter control ensures the catalyst layers are thick enough for effective purification but thin enough to maintain low flow resistance.
3Reliability
If the catalyst layers are extended along the substrate length to improve purification performance, then the purification performance improves, but the device complexity increases
Solution Approach 1:
The patent employs local quality by creating distinct inflow side catalyst layers and outflow side catalyst layers with different characteristics (Pd-containing and Rh-containing respectively). Each region is optimized for its specific function: the inflow side handles initial exhaust gas treatment while the outflow side handles processed gas, achieving high overall purification performance through localized optimization rather than uniform design.
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 improves exhaust gas purification performance and reduces pressure loss by optimizing the catalyst layer distribution and coat amount, ensuring effective heating and purification even at low exhaust gas temperatures.
Implementation Method 1
The substrate contains SiC functioning as a resistance heating element
Data Source
AI summary
Provided is an electrically heated catalyst device capable of improving a purification performance when a temperature is increased by electric heating. The electrically heated catalyst device of the present disclosure includes a substrate, an inflow side catalyst layer, and an outflow side catalyst layer. The substrate contains SiC. The inflow side catalyst layer contains Pd. The outflow side catalyst layer contains Rh. The substrate includes a partition wall defining a plurality of cells extending from an inflow side end surface to an outflow side end surface. The inflow side catalyst layer is disposed on a surface of the partition wall in an inflow side catalyst region. The inflow side catalyst region extends from an inflow side end of the partition wall to an outflow side by a distance of more than 50% of a total length in the extending direction of the partition wall. The outflow side catalyst layer is disposed on a surface of the partition wall and a surface of the inflow side catalyst layer in an outflow side catalyst region. The surface of the partition wall is in a portion not overlapping with the inflow side catalyst region, and the surface of the inflow side catalyst layer is in a portion overlapping with the inflow side catalyst region. The outflow side catalyst region extends from an outflow side end of the partition wall to an inflow side by a distance of more than 50% of the total length in the extending direction of the partition wall. A total coat amount obtained by dividing a total mass of the inflow side catalyst layer and the outflow side catalyst layer by a volume of the substrate is 138 g/L or more and 150 g/L or less.