Vented Fuel Cap With Pressure Spring Biasing
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Solution Overview
Problem
Existing vented fuel tank caps fail to adequately seal the tank while allowing for pressure equalization, leading to potential tank destruction from excess pressure or vacuum, and do not facilitate quick and easy refilling and reconnection.
Innovation Solution
A vented cap design featuring a cylindrical cap body with a vacuum valve and pressure spring that biases the bottom assembly away from the cap cover, allowing for pressure equalization and sealing, and includes a stability shim for increased lateral stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a vented fill cap is used to provide pressure equalization, then tank destruction from excess pressure or vacuum is prevented, but contaminant ingression and evaporative fuel loss occur
Solution Approach 1:
The valve cap incorporates different valve mechanisms (pressure relief valve and vacuum break valve) with distinct functions in a single integrated component. The pressure relief valve allows outward flow to prevent over-pressurization, while the vacuum break valve allows inward flow to prevent vacuum collapse, enabling localized quality control for different pressure conditions
Solution Approach 2:
The valve cap acts as an intermediary device between the tank interior and the external environment. It mediates pressure equalization by selectively allowing gas flow in specific directions while blocking contaminant ingress through its valve mechanisms, thus protecting the tank without direct exposure to environmental contaminants
2Object-generated harmful factors
If a sealed cap is used to prevent contaminant ingression and evaporative loss, then pressure equalization is compromised, resulting in potential tank destruction
Solution Approach 1:
The valve cap creates localized quality differences by implementing separate pressure relief and vacuum break functions. The pressure relief valve remains closed under normal conditions to maintain sealing, while the vacuum break valve opens selectively to equalize pressure, providing localized quality control for different pressure states
Solution Approach 2:
The valve cap employs dynamic valve mechanisms that automatically open or close based on pressure conditions. The pressure relief valve opens when internal pressure exceeds external pressure, while the vacuum break valve opens when external pressure exceeds internal pressure, enabling dynamic adaptation to maintain both sealing and pressure equalization
3Reliability
If a complex valve mechanism is used to provide effective sealing and pressure equalization, then tank protection is improved, but device complexity increases
Solution Approach 1:
The valve cap merges the pressure relief valve and vacuum break valve into a single integrated component. Both valve mechanisms are housed within one cap structure, sharing common mounting features and sealing surfaces, thus reducing overall device complexity while maintaining dual functionality for pressure equalization and sealing
Solution Approach 2:
The valve cap serves multiple functions within a single device: it provides sealing to prevent contaminant ingress, contains a pressure relief valve to prevent over-pressurization, and includes a vacuum break valve to prevent vacuum collapse. This multi-functionality reduces the need for separate components, simplifying the overall system
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 provides an effective seal to prevent contaminant ingress and evaporative loss, allows for quick refilling and reconnection, and manages pressure changes to prevent tank damage, while maintaining interchangeability with existing cap bases.
Implementation Method 1
a pressure spring residing at least partially within each of the valve body portion and the cylindrical cap body, wherein the pressure spring is configured to impart a force that biases said bottom assembly away from said cap cover
Implementation Method 2
a vacuum spring to bias the vacuum valve in the first position
Data Source
AI summary
A fuel cap is described as having a top assembly and a bottom assembly slidably engaged with, and concentric to, the top assembly. The top assembly having a cap cover and a cylindrical cap body concentric with and protruding substantially perpendicularly from, an underside surface of the cap cover. The bottom assembly having a vacuum valve operatively coupled with a valve body. A wire-form keeper may slidably secure the bottom assembly to the top assembly. A pressure spring may impart a force that biases said bottom assembly away from said top assembly.