Fuel Cap Vapor Diffuser for Evaporative Emission Control
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Solution Overview
Problem
Existing passive purge fuel caps are inadequate in purging hydrocarbon adsorbing media, suffer from poor fuel vapor flow, and are prone to contamination by liquid fuel, leading to inefficient control of evaporative emissions from fuel tanks.
Innovation Solution
A fuel cap design featuring a housing with a hydrocarbon adsorbing media-containing internal chamber, a fuel vapor diffuser, and a tether, which includes a radial and axial flow distribution system to enhance vapor flow and prevent liquid fuel entry, along with a diffuser plate and filters to optimize vapor distribution and purging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a passive purge fuel cap is used, then the device complexity is reduced and ease of manufacture is improved, but the purging efficiency of hydrocarbon adsorbing media becomes inadequate and fuel vapor flow is insufficient
Solution Approach 1:
The fuel cap is divided into multiple functional chambers: a first chamber for hydrocarbon adsorption, a second chamber for vapor distribution, and a third chamber for liquid fuel containment. This segmentation allows each chamber to perform its specific function efficiently while maintaining overall system simplicity and ease of manufacture.
Solution Approach 2:
A vapor distribution system acts as an intermediary between the fuel vapor source and the hydrocarbon adsorbing media. This intermediary component optimizes vapor flow distribution across the media, enhancing purging efficiency without requiring complex active pumping systems.
2Quantity of substance
If the hydrocarbon adsorbing media capacity is increased, then the evaporative emissions control is improved, but the device complexity and manufacturing cost increase
Solution Approach 1:
The hydrocarbon adsorbing media is nested within a specifically designed chamber structure that maximizes the media capacity within the available space. The media is contained in a porous support structure that allows efficient vapor contact while maintaining a compact overall device design.
Solution Approach 2:
The patent utilizes vertical stacking of functional chambers to increase media capacity without increasing the horizontal footprint. By arranging chambers in series vertically, the design accommodates larger media capacity while maintaining a compact form factor suitable for standard fuel cap installations.
3Productivity
If the fuel cap allows greater vapor flow, then the evaporative emissions control is improved, but the liquid fuel contamination risk increases
Solution Approach 1:
Different regions of the fuel cap are designed with different properties: the upper chambers have open structures to promote vapor flow, while the lower chamber containing liquid fuel has a restricted interface with hydrophobic characteristics. This local differentiation allows high vapor permeability in critical areas while preventing liquid fuel migration to the adsorbing media.
Solution Approach 2:
Porous materials with specific pore size distributions are used in strategic locations to allow vapor passage while blocking liquid fuel. The porous structure provides capillary pressure that permits vapor flow but prevents liquid penetration, enabling high vapor flow rates without liquid contamination risk.
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 design improves vapor distribution and purging efficiency, minimizes liquid fuel contamination, and allows for a greater capacity of hydrocarbon adsorbing media, effectively reducing evaporative emissions without increasing manufacturing complexity or cost.
Implementation Method 1
The activated charcoal has a natural affinity for hydrocarbons when in direct communication with fuel vapor
Implementation Method 2
a fuel vapor diffuser, which includes a radial and axial flow distribution system to enhance vapor flow
Implementation Method 3
along with a diffuser plate and filters to optimize vapor distribution and purging
Data Source
AI summary
A closure device, such as a fuel cap, for controlling evaporative emissions from a fuel tank. In one aspect, the invention comprises: a housing defining an internal chamber about a central axis; a diffuser plate positioned within the internal chamber that separates the internal chamber into an upper zone and a lower zone; a hydrocarbon adsorbing media disposed in the upper zone of the internal chamber; an inlet passageway for introducing fuel vapor from a fuel vapor inlet port to the lower zone of the internal chamber; and at least one outlet passageway extending from the upper zone of the internal chamber to an atmospheric air outlet port.