Capless Fuel Filler Closure With Bypass Pressure Venting
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Solution Overview
Problem
Existing tank filler pipe closures either require a cap that can be lost or do not effectively manage pressure and vacuum conditions within the fuel filler pipe, leading to inefficiencies and potential leaks during fuel refueling.
Innovation Solution
A capless filler pipe closure system that includes a nozzle-insertion housing with outer and inner flapper doors and a pressure management system to regulate pressure and vacuum by venting through independent pathways that bypass the internal cavity, ensuring the fuel within the cavity remains sealed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a traditional cap is used to close the filler pipe, then the filler pipe can be sealed, but the cap can be lost and does not effectively manage pressure and vacuum conditions
Solution Approach 1:
The flapper door automatically opens when fuel is dispensed and automatically closes when dispensing stops, eliminating the need for manual cap operation. The system serves itself by using the fuel flow to trigger door opening and spring force to close the door, removing caps entirely from the system.
Solution Approach 2:
The cap is completely removed from the system and replaced with an automatic flapper door mechanism. The harmful element (cap that can be lost) is extracted and replaced with a more reliable automatic sealing system that integrates directly into the filler pipe structure.
2Reliability
If pressure and vacuum are not managed, then the structure remains simple, but pressure buildup and vacuum conditions cause leaks and inefficiencies
Solution Approach 1:
A spring mechanism acts as an intermediary between the flapper door and the closing force, providing controlled pressure management. The spring allows the door to open under fuel pressure while maintaining sealing force during normal operation, mediating between the conflicting requirements of easy opening and reliable sealing.
Solution Approach 2:
The system uses fuel pressure itself to open the flapper door during dispensing, eliminating the need for external actuators. The hydraulic pressure from the fuel stream directly acts on the door to overcome spring force and open the seal, using the process fluid to control the mechanism.
3Ease of operation
If flapper doors are used to seal the filler pipe, then capless operation is achieved, but gaps between components can allow fuel vapor permeation
Solution Approach 1:
The flapper door assembly uses composite construction with the door body and integrated seal made from materials that resist fuel vapor permeation. The seal portion is specifically designed with low-permeability materials to prevent hydrocarbon emissions while maintaining the capless operational advantage.
Solution Approach 2:
A flexible perimeter seal is integrated into the flapper door assembly, creating a gas-tight barrier that conforms to the mating surface. This flexible film seal prevents fuel vapor leakage through gaps while allowing the door to open and close smoothly, addressing both operational ease and emission prevention.
4Reliability
If the internal cavity is vented to manage pressure, then pressure control is improved, but fuel within the cavity may be disturbed and hydrocarbons released
Solution Approach 1:
The venting system is segmented into separate pathways: one for pressure relief that bypasses the internal cavity, and another for vacuum relief. This segmentation allows pressure management without disturbing the fuel in the cavity, preventing hydrocarbon emissions while maintaining pressure control.
Solution Approach 2:
A bypass pathway acts as an intermediary route for pressure venting, allowing excess pressure to be relieved without passing through the internal cavity containing fuel. This intermediary path prevents disturbance of the fuel while still achieving pressure control, eliminating the trade-off between pressure management and emission prevention.
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 capless closure system effectively seals the fuel filler pipe without a cap, manages pressure and vacuum conditions efficiently, and prevents fuel vapor from permeating through gaps, thereby enhancing sealing performance and reducing hydrocarbon emissions.
Implementation Method 1
The perimeter seal is fixed to the door panel via a chemically bonded interface and via a mechanical fastening feature. The chemically bonded interface provides a gas tight connection between the door panel and the perimeter seal.
Implementation Method 2
the pressure management means is configured to relieve pressure in the fuel filler pipe over a preselected value by venting a flow of vapor from the fuel filler pipe to atmosphere through an overpressure path that bypasses the inner aperture, the internal chamber, and the outer aperture
Implementation Method 3
The pressure management means is further configured to relieve vacuum developed in the fuel filler pipe over a preselected value by venting a flow of air from atmosphere to the fuel filler pipe through an underpressure path that bypasses the outer aperture, the internal chamber, and the inner aperture
Data Source
AI summary
A capless closure is provided for a tank filler pipe. The capless closure permits a fuel pump nozzle to be inserted into the tank filler pipe without first removing a fuel cap from the outer end of the tank filler pipe.