Low Emission Adsorbent for Hybrid Vehicle Diurnal Breathing Loss
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Solution Overview
Problem
Current evaporative emission control systems face challenges in achieving low diurnal breathing loss (DBL) emissions, especially in hybrid vehicles and other powertrain designs with reduced purge frequencies and volumes, due to the high working capacity of adsorbents leading to excessive bleed emissions, which complicates fuel/air mixture management and increases system complexity and cost.
Innovation Solution
An adsorbent composition comprising 10-50 wt% activated adsorbent material, 3-40 wt% glass microspheres, and 0-5 wt% silica sol, with optional organic and inorganic binders, is extruded to form a honeycomb structure that demonstrates improved emissions performance and manufacturing advantages, including reduced wear on extrusion dies and lower production costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If high working capacity adsorbent materials are used to improve vapor adsorption capacity, then adsorption capacity is improved, but diurnal breathing loss emissions increase
Solution Approach 1:
The patent applies local quality by creating a bimodal pore size distribution with distinct micropore and mesopore regions. The micropores (0.003-0.006 micrometer) provide high adsorption capacity for fuel vapors, while the mesopores (0.006-0.02 micrometer) facilitate vapor transport and reduce diffusion resistance. This localized functional differentiation allows the adsorbent to achieve both high capacity and low emissions by optimizing each pore size range for its specific function rather than using a uniform pore structure
Solution Approach 2:
The patent employs composite materials by combining activated carbon with specific pore-forming agents and binders to create an extruded monolithic structure. The composite formulation includes activated carbon particles, pore-forming agents that create the bimodal pore structure, and binders that hold the structure together. This composite approach enables simultaneous achievement of high adsorption capacity, low DBL emissions, and structural integrity for extrusion processing
2Loss of energy
If purge frequency and volume are reduced in hybrid vehicles, then fuel economy is improved, but DBL emissions control becomes more difficult
Solution Approach 1:
The patent applies preliminary action by designing an adsorbent material with pre-optimized bimodal pore structure that proactively addresses the DBL emissions problem before it occurs. The mesopores are pre-formed to provide low resistance vapor transport pathways, and the micropores are pre-configured for high capacity. This preliminary structural optimization allows the system to maintain low emissions even when purge operations are minimized in hybrid vehicles, as the adsorbent inherently resists bleed emissions through its designed pore architecture rather than requiring frequent active purging
3Ease of manufacture
If conventional adsorbent formulations are used, then manufacturing process is simple, but wear on extrusion dies increases
Solution Approach 1:
The patent applies this principle by formulating an extruded adsorbent composition that is optimized for extrusion processing, accepting that the extrusion die will experience wear during the manufacturing process. The formulation includes binders and pore-forming agents that facilitate smooth extrusion, and the process is designed to be relatively simple and cost-effective. The wear on the extrusion die is considered an acceptable cost of production that is replaced periodically, while the resulting adsorbent product achieves superior performance with low DBL emissions
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 described adsorbent composition achieves DBL emissions of 100 mg or less at specified purge air volumes, meeting regulatory limits while being more cost-effective and simpler in design, with enhanced manufacturing efficiency and emissions control.
Implementation Method 1
The adsorbent material comprises from about 10 to about 50 wt % activated adsorbent material
Implementation Method 2
from about 3 to about 40 wt % glass microspheres
Data Source
AI summary
The present description provides adsorbent compositions and materials, and systems comprising the same that provide low DBL bleed emission performance. The described materials provide unexpected production advantages as compared to currently available materials.