Fuel Tank Volume Element Structure for Hydrocarbon Emission Control
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Solution Overview
Problem
Hydrocarbon emissions from fuel tanks in motor vehicles are a concern due to their environmental impact, with challenges including permeation through the tank wall, refueling processes, and diurnal emissions, especially in hybrid vehicles where the internal combustion engine is not always operational.
Innovation Solution
A fuel tank design featuring a gas-filled volume element made of flexible material that changes volume to compensate for pressure changes and temperature-induced vapor pressure fluctuations, with stabilization arrangements to prevent damage and leakage, allowing for efficient gas exchange and minimal hydrocarbon emissions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a rigid tank structure is used to maintain structural integrity, then strength is improved, but the ability to compensate for gas volume changes is worsened
Solution Approach 1:
The patent employs a flexible bladder made of elastomeric material that can deform and change volume in response to pressure differences. This flexible shell allows the tank to adapt to gas volume changes while maintaining structural integrity through the surrounding rigid tank walls. The bladder's flexibility enables it to expand and contract without compromising the overall tank strength.
Solution Approach 2:
The tank system is divided into separate functional components: a rigid outer tank structure for strength and a flexible inner bladder for volume compensation. This segmentation allows each component to perform its specialized function - the rigid tank provides structural support while the flexible bladder handles gas volume adjustments independently.
2Adaptability or versatility
If a flexible volume element is used to compensate for gas volume changes, then adaptability is improved, but emission tightness is worsened
Solution Approach 1:
The bladder is constructed from composite materials combining different elastomeric layers with varying properties. The multi-layer construction provides both the necessary flexibility for volume compensation and sufficient barrier properties to reduce hydrocarbon permeation. The composite structure balances mechanical compliance with emission resistance.
Solution Approach 2:
The flexible bladder acts as an intermediary between the liquid fuel and the gas space. It selectively accommodates gas volume changes while maintaining a barrier that prevents direct contact between fuel vapors and the external environment, thereby reducing emissions. The bladder mediates the interaction between pressure changes and fuel containment.
3Ease of operation
If the volume element is made highly deformable to ensure complete filling and emptying, then ease of operation is improved, but reliability is worsened due to potential damage
Solution Approach 1:
The bladder design incorporates predetermined fold lines and crease patterns that guide deformation in controlled locations. These pre-designed flexibility zones allow the bladder to bend and deform during filling and emptying operations without creating unpredictable stress concentrations that could lead to failure. The cushioning effect is built into the geometry rather than relying on material compliance alone.
Solution Approach 2:
The bladder transitions from a static rigid structure to a dynamic flexible form that adapts its shape during operation. The ability to dynamically change volume and shape during filling and emptying cycles enables complete evacuation while the controlled flexibility patterns maintain structural integrity throughout the motion.
4Object-generated harmful factors
If the volume of the volume element is increased to compensate for saturation vapor pressure, then hydrocarbon emissions are reduced, but device complexity is worsened
Solution Approach 1:
The flexible bladder performs multiple functions simultaneously: it compensates for gas volume changes during filling, accommodates thermal expansion of fuel, maintains pressure balance, and reduces hydrocarbon emissions. This multi-functionality eliminates the need for separate components for each function, thereby reducing overall system complexity despite the increased volume requirement.
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 tank design effectively reduces hydrocarbon emissions by maintaining a pressure-neutral gas volume, minimizing kinks and damage, and enabling safe operation with reduced maintenance, particularly suitable for hybrid vehicles.
Implementation Method 1
temperature-induced vapor pressure fluctuations
Implementation Method 2
gas-filled volume element made of flexible material that changes volume
Implementation Method 3
gas, in particular air, being pushed out or sucked in from the volume element 4 through the line 5
Implementation Method 4
stabilization arrangement 6 for minimizing stresses at these kinks in the volume element 4
Data Source
Figure 1~2
Figure 3~4
Figure 4A
AI summary
The invention relates to a tank, in particular a fuel tank, for receiving a fluid in a motor vehicle, comprising an outer wall forming an internal space for receiving the fluid, at least one volume element arranged in the internal space for receiving gas, in particular air, a gas-guiding line between the volume element and the environment of the tank for changing the volume of the volume element, and at least one stabilising assembly for minimising stresses at kinks of the volume element when evacuating the volume element.