Tortuous Flow Restricting Plug for Fuel Vapor Recirculation

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Solution Overview

Problem

Existing fuel vapor recirculation systems in motor vehicles face challenges in preventing liquid fuel from entering the vapor recirculation pipe during refueling, particularly due to nozzle malfunctions or operator errors, which can lead to inefficient vapor recovery and environmental emissions.

Innovation Solution

A flow-restricting plug made of fuel-impervious material with a tortuous passage on its outer surface is designed to differentiate between vapor and liquid flow, allowing vapor to pass while restricting liquid fuel entry into the vapor recirculation pipe, utilizing a cylindrical shape and meandering channels that facilitate easy manufacturing and effective flow discrimination.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If an orifice-like plug is used to allow metered vapor flow, then vapor recirculation is enabled, but liquid fuel flow is not effectively prevented

Engineering Contradiction:

Improvevapor recirculation effectivenessVSAvoidliquid fuel contamination

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The plug incorporates a porous body with interconnected pores that allow vapor molecules to pass through while physically blocking liquid fuel due to capillary forces and surface tension effects at the pore scale

Inventive Principle:

Principle #31Porous materials

Solution Approach 2:

The plug features a flow passage with tortuous geometry that creates localized flow paths optimized for vapor transmission while the porous structure provides localized resistance to liquid penetration, differentiating behavior based on fluid phase

Inventive Principle:

Principle #3Local quality

2Ease of manufacture

If a simple orifice plug is used, then manufacturing is simple, but flow discrimination between vapor and liquid is insufficient

Engineering Contradiction:

Improveplug fabrication simplicityVSAvoidflow discrimination capability

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The porous structure can be integrated during molding or by incorporating a porous substrate, maintaining manufacturing feasibility while enabling superior vapor-liquid discrimination through capillary action and surface area effects

Inventive Principle:

Principle #31Porous materials

Solution Approach 2:

The flow passage is configured with tortuous three-dimensional paths rather than simple straight orifices, creating multiple flow dimensions that enhance vapor transmission through surface area while maintaining liquid blocking capability

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

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 plug effectively prevents liquid fuel from entering the vapor recirculation pipe, ensuring efficient vapor recovery and reducing emissions by allowing vapor to flow freely while blocking liquid fuel, thus enhancing the onboard vapor recovery system's performance.

Implementation Method 1

The tortuous shape of the flow passage permits the flow of fuel vapor through the plug but prevents the flow of liquid fuel through the plug

Methodology Applied

Scientific EffectPhase-dependent flow resistance:

Data Source

PatentUS7614431B2Fuel flow restriction plug for recirculation pipe

Publication Date: 2009.11.10 GM GLOBAL TECHNOLOGY OPERATIONS LLC

AI summary

A flow-restricting plug is provided for installation within a vapor recirculation pipe that communicates with a fuel filler pipe. The plug is manufactured of fuel-impervious material and has a cylindrical shape adapted to be mounted by press fit within the vapor recirculation pipe. A flow passage of tortuous shape is formed along the outer circumferential surface of the plug between the opposed ends thereof. The tortuous shape of the flow passage permits the flow of fuel vapor through the plug but prevents the flow of liquid fuel through the plug.