Vehicle Side Sill Energy Absorber for Crash Deformation Control

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Solution Overview

Problem

Conventional motor vehicle side skirts in shell construction lack sufficient deformation resistance during side crashes, leading to potential deformation of the floor assembly under external forces.

Innovation Solution

Incorporating an energy absorber with a honeycomb structure made of thermoplastic material like PC+PBT, surrounded by an intermediate plastic foam layer and a carbon fiber reinforced plastic tie, within the cavity between the inner and outer shells of the side sill, to absorb and distribute forces effectively.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If a conventional shell construction side skirt is used, then the structure is simple and lightweight, but the deformation resistance during side crashes is insufficient

Engineering Contradiction:
Improvedeformation resistanceVSAvoidstructure complexity
Core Design Contradiction:
StrengthVSDevice complexity

Solution Approach 1:

The patent applies composite materials by combining thermoplastic material (PC+PBT) for the energy absorber, plastic foam for the intermediate layer, and carbon fiber reinforced plastic for the tension band. This multi-material composite structure achieves high deformation resistance while managing the complexity through functional specialization of each material layer.

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The patent implements local quality by placing the energy absorber specifically in the middle region of the side skirt where crash forces are most critical. The honeycomb structure provides localized high-strength energy absorption exactly where needed, rather than uniformly strengthening the entire side skirt structure.

Inventive Principle:
Principle #3Local quality

2Use of energy by moving object

If the cavity between inner and outer shells is left empty, then the side skirt structure remains simple, but it cannot absorb crash forces effectively

Engineering Contradiction:
Improveenergy absorptionVSAvoidstructure complexity
Core Design Contradiction:
Use of energy by moving objectVSDevice complexity

Solution Approach 1:

The patent applies the nesting principle by placing the energy absorber with honeycomb chambers inside the cavity between the inner and outer shells. The intermediate layer and tension band are further nested within this structure, creating a multi-layer nested configuration that maximizes energy absorption while containing the complexity within a compact form factor.

Inventive Principle:
Principle #7Nested doll (Nesting)

Solution Approach 2:

The patent utilizes porous materials by employing the honeycomb structure of the energy absorber made from thermoplastic material. The honeycomb chambers create a porous configuration that enables progressive collapse and energy absorption during side crashes, transforming the empty cavity into an active energy management system.

Inventive Principle:
Principle #31Porous materials

3Reliability

If no reinforcement is added to the side skirt, then manufacturing remains simple, but the floor assembly is vulnerable to deformation under side forces

Engineering Contradiction:
Improvefloor assembly protectionVSAvoidmanufacturing complexity
Core Design Contradiction:
ReliabilityVSEase of manufacture

Solution Approach 1:

The patent applies preliminary action by pre-installing the energy absorber, intermediate layer, and tension band into the side skirt structure before final assembly. These reinforcement elements are positioned in advance to provide immediate structural support and floor assembly protection, rather than requiring complex post-assembly reinforcement procedures.

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

The solution significantly increases the rigidity of the side skirt, protects the floor assembly from deformation, and allows for efficient absorption of crash energy by distributing forces evenly, enhancing the side skirt's ability to withstand side crashes without excessive deformation.

Implementation Method 1

The energy absorber according to the invention absorbs at least part of these acting forces through deformation

Methodology Applied
Scientific EffectDeformation: Deformation

Implementation Method 2

the intermediate layer stabilizes the energy absorber so that it does not tilt and can absorb additional deformation energy

Methodology Applied
Scientific EffectEnergy absorption: Absorption (physical)

Implementation Method 3

the tension band, which can consist of a carbon fiber reinforced plastic, for example, is applied to the side of the energy absorber facing the inner shell of the side skirt or to the side of the inner shell facing the center of the vehicle. This tie strengthens the side skirt and can, above all, absorb the tensile stresses that occur on the inside of the side skirt

Methodology Applied
Scientific EffectTensile stress absorption: Tension

Data Source

PatentEP2571747B1Motor vehicle having a side sill
Publication Date: 2015.03.18 BAYERISCHE MOTOREN WERKE AG
  • EP2571747B1 patent drawingFigure 1
  • EP2571747B1 patent drawingFigure 2
  • EP2571747B1 patent drawingFigure 3~4

AI summary

In vehicle construction today, most side skirts have a shell-type design. Such a side skirt comprises at least one inner shell and an outer shell, which are interconnected on two flanges extending in the longitudinal direction of the vehicle and in between enclose a cavity when viewed in cross-section. It is the aim of the invention to create a motor vehicle comprising a side skirt which has a small deformation path during a side crash. According to the invention, an energy absorber (3) is located in the cavity (8) between an inner shell (5) and an outer shell (4) of a side skirt (2), at least in the central region of the side skirt (2) - when viewed in the longitudinal direction of the vehicle (x).