Vehicle Armrest Flexible Rod Structure for Overload Protection

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Solution Overview

Problem

Existing armrest designs for vehicles, particularly buses, are complex due to special cast components and lack a simple design while providing effective overload protection.

Innovation Solution

An armrest design featuring a flexible rod that pivots with the armrest body, supported by stops on the seat structure, which yields under overload to protect the armrest from damage, allowing it to withstand loads of at least 80 daN without changing position under normal loads.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a pressure-spring-loaded piston-cylinder unit is used for overload protection, then the armrest is protected from damage under overload, but the design becomes complex due to special cast components

Engineering Contradiction:
Improveoverload protectionVSAvoidcomplexity of cast components
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The invention extracts the complex piston-cylinder unit and replaces it with a simple flexible rod that can be easily integrated into the armrest structure. The flexible rod is guided by a holding element and supported at its ends by support stops, eliminating the need for special cast components while maintaining overload protection functionality.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The invention changes the physical state and properties of the rod from rigid to flexible. By using a flexible rod with appropriate bending resistance, the system achieves overload protection through elastic deformation rather than mechanical locking mechanisms, significantly simplifying the overall design.

Inventive Principle:
Principle #35Parameter changes

2Strength

If the armrest is designed to withstand high loads (80 daN), then durability is improved, but the structure becomes more complex and less adaptable

Engineering Contradiction:
Improveload bearing capacityVSAvoidstructural complexity
Core Design Contradiction:
StrengthVSDevice complexity

Solution Approach 1:

The invention achieves high load bearing capacity by optimizing the bending resistance parameter of the flexible rod. The rod is designed with specific material properties and geometric characteristics that allow it to withstand normal loads (30 daN) without excessive deflection while yielding under overload conditions (80 daN), providing both strength and simplicity.

Inventive Principle:
Principle #35Parameter changes

3Stability of the object's composition

If the holding element grips the bending rod tightly in both pivoting directions, then the rod is securely held, but the armrest cannot perform additional downward swing under overload

Engineering Contradiction:
Improvesecuring of bending rodVSAvoiddownward swing capability
Core Design Contradiction:
Stability of the object's compositionVSAdaptability or versatility

Solution Approach 1:

The holding element is designed with asymmetric gripping characteristics: it securely holds the flexible rod during upward pivoting (normal operation) but allows the rod to slide or yield during downward pivoting (overload condition). This asymmetric design enables the system to maintain stability during normal use while providing adaptability for overload protection through additional downward swing.

Inventive Principle:
Principle #4Asymmetry

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 design provides effective overload protection while maintaining a simple structure, ensuring the armrest remains stable under normal loads and absorbs excess loads to prevent damage, with a symmetrical load distribution and secure engagement of the flexible rod.

Implementation Method 1

the bending rod, both ends of which are fixed to the support stops formed on the seat structure, yields elastically and thereby protect the armrest structure from damage

Methodology Applied
Scientific EffectElasticity: Elasticity

Data Source

PatentEP2172134B1Armrest
Publication Date: 2011.01.26 GRAMMER AG
  • EP2172134B1 patent drawingFigure 1
  • EP2172134B1 patent drawingFigure 2
  • EP2172134B1 patent drawingFigure 3

AI summary

The armrest has an armrest body pivotable between raised and lowered positions around a pivoting axis (x) that supports a sitting structure (28). The body directly supports at a support stop (30) against a spring resetting force corresponding to a downward pivoting direction (u) in the lowered position. The body guides pivoting of a bent bar (15) by a holding element (17) that is movably integrated with the body. Two free ends (22) of the bar support against the stop formed at the sides of the structure in a resting position of the armrest body corresponding to the downward pivoting direction.