Fuel Tank Internal Bracket Layout to Limit Swelling and Slosh

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Solution Overview

Problem

Thermoplastic fuel tank brackets tend to swell when in contact with fuel, reducing the fuel volume capacity and requiring a larger tank size, which limits the tank's geometry and fit within vehicle spaces, and also causes sloshing noise due to their monolithic structure.

Innovation Solution

A blow molded thermoplastic fuel tank with separate and spaced internal brackets that support individual fuel system components, minimizing thermoplastic exposure to fuel and allowing for complex shapes, thinner designs, and noise reduction through baffle-like functionality, along with a jig system for precise placement and pressure monitoring during the blow molding process.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If a monolithic internal bracket is used to mount fuel system components, then the bracket provides structural support and component mounting capability, but the thermoplastic material swells when in contact with fuel, reducing fuel volume capacity and requiring a larger tank size

Engineering Contradiction:

Improvebracket structural supportVSAvoidfuel volume capacity

Core Design Contradiction:

StrengthVSVolume of stationary object

Solution Approach 1:

The monolithic bracket is divided into multiple separate brackets, each mounted at different locations on the tank interior. This segmentation reduces the total volume of thermoplastic material in contact with fuel, minimizing swelling effects and maximizing fuel capacity while maintaining structural support functionality through distributed mounting points

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Brackets are strategically positioned at specific locations where structural support is most needed, rather than using a large monolithic structure. This allows the tank geometry to be optimized for fuel capacity in regions where brackets are not present, while maintaining adequate support at critical locations

Inventive Principle:

Principle #3Local quality

2Ease of manufacture

If a monolithic internal bracket is used, then component mounting is achieved, but the bracket size affects fuel tank geometry and requires a larger volume and size for the tank

Engineering Contradiction:

Improvecomponent mounting capabilityVSAvoidtank geometry flexibility

Core Design Contradiction:

Ease of manufactureVSShape

Solution Approach 1:

The bracket system is segmented into multiple smaller brackets distributed throughout the tank interior. This allows each bracket to be independently sized and positioned to match the specific mounting requirements of individual fuel system components, enabling complex tank geometries and thinner overall tank design while maintaining ease of component mounting

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Multiple brackets are positioned at different locations and orientations within the tank interior, utilizing three-dimensional space efficiently. This distributed arrangement allows the tank to achieve complex contoured shapes and fit within tighter vehicle spaces while providing adequate mounting surfaces for all components

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

3Device complexity

If a monolithic bracket structure is used, then all components are supported on a single structure, but the structure acts as a baffle causing sloshing noises of liquid fuel in the tank

Engineering Contradiction:

Improvebracket structure simplicityVSAvoidsloshing noise

Core Design Contradiction:

Device complexityVSObject-generated harmful factors

Solution Approach 1:

The single monolithic bracket is replaced with multiple separate brackets distributed throughout the tank. This segmentation breaks up the continuous baffle effect that causes fuel sloshing noise, while the distributed arrangement of multiple smaller brackets provides equivalent structural support for all components without generating harmful noise

Inventive Principle:

Principle #1Segmentation

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

Maximizes fuel volume capacity, provides design flexibility for the tank's shape and size, reduces noise from sloshing, and ensures optimal component placement and function by minimizing thermoplastic swelling and exposure, while maintaining precise tolerances and pressures during manufacturing.

Implementation Method 1

The separate brackets also act as baffles to prevent sloshing noises of liquid fuel in the tank

Methodology Applied

Scientific EffectBaffle effect:

Implementation Method 2

Thermoplastic materials employed for such a bracket, due to interaction with fuel, have a certain tendency to swell which can affect the fill volume of the tank

Methodology Applied

Scientific EffectThermoplastic swelling:

Data Source

PatentUS11794571B1Blow molded fuel tank with separate internal brackets

Publication Date: 2023.10.24 HONDA MOTOR CO LTD

AI summary

A blow molded thermoplastic fuel tank with built-in fuel system components inside of the tank on separate and spaced apart internal brackets reduces the detrimental effects of thermoplastic swell to ensure fuel volume capacity is maximized, and appropriate clearances with the fuel tank wall are maintained. An internal configuration with separate spaced apart brackets provides more design freedom in the shape and configuration of the tank while enabling the tank shape to be thinner overall and fit within tighter spaces. The separate brackets also act as baffles to prevent sloshing noises of liquid fuel in the tank.