Coated Hydrocarbon Adsorbent Substrate for Low-DBL Emission Control
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Solution Overview
Problem
Current evaporative emission control systems for motor vehicles face challenges in reducing diurnal breathing loss (DBL) emissions, especially in hybrid vehicles with reduced purge volumes, and struggle to minimize space and weight while effectively adsorbing hydrocarbon emissions from fuel systems and air intake systems without increasing air intake restriction.
Innovation Solution
A coated substrate with a hydrocarbon adsorbent coating comprising particulate carbon and a binder, having a high BET surface area and n-butane adsorption capacity, is integrated into the air intake system and evaporative emission control canister system to adsorb and desorb hydrocarbons efficiently, reducing DBL emissions and optimizing space and weight.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If carbon-containing honeycomb adsorbents are used to control evaporative emissions, then pressure drop is reduced, but diurnal breathing loss emissions increase due to insufficient adsorption capacity
Solution Approach 1:
The patent applies composite materials by combining activated carbon particles with a binder matrix to create a coated substrate. This composite structure integrates the high adsorption capacity of activated carbon with the structural integrity of the binder, resolving the contradiction between maintaining adsorption capacity and reducing pressure drop. The coated substrate form factor further optimizes flow characteristics while preserving adsorption functionality.
Solution Approach 2:
The patent utilizes porous materials by employing activated carbon with high surface area and porous structure within the coated substrate. The porous nature of activated carbon provides extensive adsorption sites for hydrocarbon vapors, while the controlled porosity and particle size distribution ensure optimal gas flow through the substrate, addressing both adsorption capacity and pressure drop requirements.
2Object-generated harmful factors
If larger adsorbent volumes are used to reduce DBL emissions, then adsorption capacity increases, but device weight and space requirements increase
Solution Approach 1:
The patent applies parameter changes by optimizing the particle size distribution, surface area, and pore structure of the activated carbon within the coated substrate. By carefully controlling these parameters, the adsorption capacity is maximized per unit mass and volume, allowing effective DBL emission control with a compact, lightweight device configuration rather than requiring large adsorbent volumes.
Solution Approach 2:
The patent applies local quality by creating a coated substrate where the adsorbent material is distributed as a coating on a support structure. This configuration provides high adsorption capacity at the surface interfaces where vapor contact occurs, while the overall device maintains reduced weight and volume compared to bulk adsorbent configurations. The coating approach concentrates adsorption functionality where it is most effective.
3Object-generated harmful factors
If more frequent or larger volume purge cycles are implemented, then residual hydrocarbon heel is reduced, but energy consumption and system complexity increase
Solution Approach 1:
The patent applies preliminary action by designing the coated substrate with optimized adsorption characteristics that prevent excessive hydrocarbon accumulation during the adsorption phase. The high surface area and controlled pore structure of the activated carbon coating enable more complete adsorption of vapor during normal operation, reducing the amount of residual heel that would require intensive purging. This preliminary effective adsorption reduces the energy burden on subsequent purge operations.
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 solution effectively reduces DBL emissions to below 20 mg under stringent regulations, maintains low weight and space requirements, and enhances hydrocarbon adsorption capacity, even under low purge conditions, by utilizing a coated substrate with high BET surface area and n-butane adsorption capacity in the air intake and evaporative emission control systems.
Implementation Method 1
a hydrocarbon adsorbent coating comprising particulate carbon and a binder, having a high BET surface area and n-butane adsorption capacity
Implementation Method 2
desorbing the fuel vapor from the activated carbon and thereby regenerating the carbon for further adsorption of fuel vapor
Data Source
AI summary
The present disclosure relates to hydrocarbon emission control systems. More specifically, the present disclosure relates to substrates coated with hydrocarbon adsorptive coating compositions, air intake systems, and evaporative emission control systems for controlling evaporative emissions of hydrocarbons from motor vehicle engines and fuel systems.