Vehicle Lumbar Support Elastic Member Anti-Whiplash Mechanism

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Solution Overview

Problem

Existing lumbar supports for vehicle seats face issues with unwanted shifting of elastic members during normal driving conditions, leading to maintenance needs, and fail to effectively provide the 'anti-whiplash' function without increasing the number of components.

Innovation Solution

A lumbar support system utilizing an elastic member with a specific characteristic curve, connecting the rest member to the backrest frame, which maintains a balanced position under normal conditions and shifts rearward upon exceeding a force threshold to prevent whiplash during rear impacts, using a single leaf spring made of metal or plastic with a designed shape and size to ensure effective 'anti-whiplash' functionality.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If elastic members are used to maintain the rest member in an advanced balanced position, then the lumbar support provides normal support function, but the elastic members may shift during normal driving conditions causing maintenance needs

Engineering Contradiction:
Improvestability of elastic membersVSAvoidmaintenance requirements
Core Design Contradiction:
ReliabilityVSEase of manufacture

Solution Approach 1:

The patent modifies the physical parameters of the elastic member by introducing a rigid portion with specific geometric characteristics (width, thickness, length ratios) and material properties (elastic modulus). This changes the stiffness distribution along the elastic member, creating zones of different flexibility that prevent unwanted shifting during normal driving while maintaining the ability to provide anti-whiplash protection during accidents.

Inventive Principle:
Principle #35Parameter changes

2Object-affected harmful factors

If the elastic members are designed to shift during rear impact for anti-whiplash function, then safety is improved, but the members may also shift during normal driving causing false movements

Engineering Contradiction:
Improvewhiplash protectionVSAvoidunwanted shifting during normal use
Core Design Contradiction:
Object-affected harmful factorsVSEase of operation

Solution Approach 1:

The patent applies local quality by creating different structural zones within the elastic member. The rigid portion has different dimensional ratios (width/thickness and length/thickness) that create localized stiffness variations. This allows the elastic member to exhibit different behavioral characteristics in different regions, preventing false movements during normal use while enabling the required displacement for anti-whiplash protection during accidents.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The patent implements dynamics by designing the elastic member with a rigid portion that can transition between different structural states. Under normal driving conditions, the rigid portion maintains a stable configuration that prevents unwanted shifting. During rear impact, the same rigid portion dynamically transitions to allow the necessary backward movement of the rest member for whiplash protection.

Inventive Principle:
Principle #15Dynamics

3Device complexity

If a simple elastic member design is used, then the component count remains low, but the anti-whiplash function is not effectively provided

Engineering Contradiction:
Improvenumber of componentsVSAvoidanti-whiplash effectiveness
Core Design Contradiction:
Device complexityVSReliability

Solution Approach 1:

The patent applies segmentation by dividing the elastic member into distinct functional portions: a flexible portion and a rigid portion with specific geometric characteristics. This segmentation allows each portion to perform its specialized function - the flexible portion allows movement while the rigid portion provides structural stability and prevents false shifting - while still being part of a single integrated component that maintains low device complexity.

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

The system provides effective 'anti-whiplash' protection during rear impacts while maintaining comfort under normal conditions, with automatic return to the initial position post-collision, reducing maintenance needs and maintaining a low component count.

Implementation Method 1

an elastic member (15), which causes, by its deformation, the rest member (12) to shift backwards

Methodology Applied
Scientific EffectElastic deformation: Elasticity

Implementation Method 2

automatic return to the initial position post-collision

Methodology Applied
Scientific EffectElastic recovery: Elastic Recovery

Data Source

PatentEP2529974B1Lumbar support for a vehicle backrest
Publication Date: 2015.01.07 CENTRO RICERCHE FIAT SCPA
  • EP2529974B1 patent drawingFigure 1
  • EP2529974B1 patent drawingFigure 2~3

AI summary

A lumbar support (1) for a vehicle backrest is provided with a rest member (12) having a front surface shaped to support an area (5) of a user's back. Behind the rest member (12) an elastic member (15) is provided, which has a middle portion (19) fixed to the rest member (12) and two opposing ends (17), which are designed to be connected to a backrest frame, the elastic member (15) being designed to maintain the rest member (12) in a rest position and to deform in response to a thrust of the user's back to backwardly release the rest member (12) between the rest position and a first position (D1) under normal use conditions, and then abruptly towards a second position (D2) when a thrust of a user's back exceeds a given force value (F1). The characteristic force/displacement curve of the elastic member (15) has a slope between zero and a given threshold (V) in the section between the first and the second positions (D1, D2), and the threshold (V) being equal to 0.5 [N/mm].