Vehicle Subframe Reinforcement Using Expandable Pre-foam

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Solution Overview

Problem

Modern vehicle subframes face a challenge in achieving both lightweight and sufficient stiffness to enhance fuel efficiency and reduce manufacturing costs, as thin metal-sheet parts used to minimize weight compromise structural integrity.

Innovation Solution

The method involves using topology optimization to identify high-stress areas in the subframe, where a reinforcement part with a lightweight Polyamide carrier and expandable pre-foam is inserted and secured, allowing the metal-sheet part to be thinned while maintaining structural support.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Weight of moving object

If the thickness of the metal-sheet part of the subframe is reduced to decrease weight, then the weight of the subframe is reduced, but the stiffness of the subframe becomes insufficient

Engineering Contradiction:
Improveweight of subframeVSAvoidstiffness of subframe
Core Design Contradiction:
Weight of moving objectVSStrength

Solution Approach 1:

The patent combines metal-sheet parts with polymer foam materials to create a composite structure. The metal-sheet provides structural framework while the foam material provides reinforcement and stiffness. This composite approach allows the metal-sheet to be thinner while maintaining overall structural rigidity, thus reducing weight without sacrificing stiffness.

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The patent applies foam material reinforcement specifically at high-stress areas identified through topology optimization, rather than uniformly throughout the entire subframe. This localized reinforcement provides necessary stiffness where needed while keeping other areas lightweight, resolving the contradiction between overall weight reduction and local stiffness requirements.

Inventive Principle:
Principle #3Local quality

2Strength

If topology optimization is used to identify reinforcement areas and foam material is added, then the stiffness of the subframe is improved, but the device complexity increases

Engineering Contradiction:
Improvestiffness of subframeVSAvoidcomplexity of subframe structure
Core Design Contradiction:
StrengthVSDevice complexity

Solution Approach 1:

The patent divides the subframe into distinct metal-sheet components and foam material components. The metal-sheet parts maintain their original structural roles while foam inserts are added as separate reinforcement elements. This segmentation allows for modular manufacturing and assembly, managing complexity by keeping components distinct rather than creating a fully integrated complex structure.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent uses topology optimization in the design phase to pre-identify areas requiring reinforcement before manufacturing. This preliminary analysis allows for optimized placement of foam materials, ensuring stiffness requirements are met while avoiding unnecessary reinforcement. The optimization process determines the minimal necessary intervention, preventing excessive complexity.

Inventive Principle:
Principle #10Preliminary action

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

This approach results in a lighter, stiffer subframe that reduces overall vehicle weight and manufacturing costs while ensuring the subframe can withstand dynamic loads effectively.

Implementation Method 1

supplying heat to the pre-foam such that it expands to secure the reinforcement part within the subframe

Methodology Applied
Scientific EffectThermal expansion: Thermal Expansion

Data Source

PatentEP3057854B1Subframe and method for reinforcing the same
Publication Date: 2019.07.24 HENKEL KGAA
  • EP3057854B1 patent drawingFigure 1
  • EP3057854B1 patent drawingFigure 2
  • EP3057854B1 patent drawingFigure 3~4

AI summary

The present invention relates to a method for reinforcing a vehicle subframe comprising one or more hollow metal-sheet parts, wherein the method comprises: a step of determining at least one area on the hollow metal-sheet part of the subframe with respect to specified conditions; a step of preparing a reinforcement part which is able to be inserted in the hollow metal-sheet part of the subframe at said area, wherein the reinforcement part comprises a lightweight carrier for supporting the metal-sheet part and a pre-foam of a foam material which is able to expand after being heated, wherein the lightweight comprises at lease one hollow chamber and wherein the pre-foam is isolated from said at least one hollow chambers and is distributed at least partly on the periphery of the carrier; and a step of installing the reinforcement part within the metal-sheet part of the subframe at the determined area and supplying heat to the pre-foam such that it expands. The present invention also relates to a vehicle subframe reinforced by said method.