Titanium Fuel Tank Springback Control

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Solution Overview

Problem

High-grade sports and race-based vehicles face challenges in achieving weight reduction with titanium fuel tanks due to titanium's low Young's modulus, leading to increased springback and variability in fuel tank capacity during press molding.

Innovation Solution

The fuel tank design incorporates titanium material with specific features such as tubular members, flanges with linear outer edges, recesses, and convex portions on the side surfaces, which reduce springback, enhance rigidity, and facilitate easy welding, while also incorporating rubber members for secure attachment to the vehicle frame.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Weight of moving object

If titanium material is used for weight reduction, then weight decreases, but springback increases causing shape accuracy deterioration

Engineering Contradiction:
Improvefuel tank weightVSAvoidshape accuracy
Core Design Contradiction:
Weight of moving objectVSManufacturing precision

Solution Approach 1:

The patent changes the material parameter from steel to titanium, accepting the trade-off of increased springback. To compensate, the design incorporates specific geometric features (recesses and convex portions) that control the springback behavior and maintain final shape accuracy despite the material change.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The press molding process is designed to account for titanium's springback characteristics in advance. By pre-calculating and compensating for the expected springback during the molding stage, the final assembled fuel tank achieves the desired shape accuracy despite using titanium material.

Inventive Principle:
Principle #10Preliminary action

2Weight of moving object

If titanium material is used, then weight reduction is achieved, but capacity variation increases

Engineering Contradiction:
Improvefuel tank weightVSAvoidcapacity consistency
Core Design Contradiction:
Weight of moving objectVSManufacturing precision

Solution Approach 1:

The patent accepts titanium material substitution while implementing compensatory geometric features. The recesses and convex portions are specifically designed to control deformation during assembly, ensuring that capacity remains consistent across multiple units despite the material's springback characteristics.

Inventive Principle:
Principle #35Parameter changes

3Ease of manufacture

If flanges are designed for welding, then joining is facilitated, but springback compensation becomes more complex

Engineering Contradiction:
Improvewelding easeVSAvoidspringback compensation complexity
Core Design Contradiction:
Ease of manufactureVSDevice complexity

Solution Approach 1:

The patent applies different geometric features to different locations: simple linear outer edges at the flange regions for easy welding, and recesses/convex portions at critical structural areas for springback control. This localized differentiation optimizes both welding ease and springback compensation without excessive complexity.

Inventive Principle:
Principle #3Local quality

Data Source

PatentEP3281854B1Fuel tank for saddled vehicle
Publication Date: 2020.06.17 HONDA MOTOR CO LTD
  • EP3281854B1 patent drawingFigure 1
  • EP3281854B1 patent drawingFigure 2
  • EP3281854B1 patent drawingFigure 3

AI summary

An upper half body flange (30a) is disposed over a whole circumference of a lower end portion of an upper half body (30) along a plane (H), and a lower half body flange (50a) is disposed over a whole circumference of an upper end portion of a lower half body (50) along the plane H. The upper half body (30) and the lower half body (50) are made of titanium material, and the upper half body flange (30a) and the lower half body flange (50a) have linear outer edges as straight line portions (T1, T2). The upper half body (30) has a side surface (US), the lower half body (50) has a side surface (DS), and the side surface (US) and the side surface (DS) include recesses (51, 56, 36, 37) and convex portions (60, 61, 62). The recesses (51, 56, 36, 37) and the convex portions (60, 61, 62) are disposed within a range of lengths of the straight line portions (T1) and (T2) when viewed from above in the direction perpendicular to the plane (H).