Elastomer Torsion Spring Seat Assembly for Linear Restoring Torque

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Solution Overview

Problem

Existing seat devices with elastomer torsion spring elements face limitations such as a small increase in restoring torque with angle of rotation, non-linear torque progression, and reduced service life due to high preload and non-linear stress distribution, leading to discomfort and frequent replacement.

Innovation Solution

A seat device with an elastomer torsion spring element featuring non-circular contact surfaces on the inner and outer housings, allowing for a steeper increase in restoring torque with a linear progression over a larger angle range, and a design that distributes tensile and compressive stresses within the elastomer body for homogeneous loading, reducing wear and extending service life.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Force

If conventional elastomer torsion spring elements with circular contact surfaces are used, then the structure is simple, but the restoring torque increases slowly and non-linearly with angle of rotation

Engineering Contradiction:
Improverestoring torqueVSAvoidcontact surface geometry
Core Design Contradiction:
ForceVSDevice complexity

Solution Approach 1:

The patent applies asymmetry by changing the contact surface geometry from circular to non-circular (e.g., rectangular, square, or other polygonal shapes). This asymmetric geometry creates a more favorable stress distribution in the elastomer body during rotation, resulting in a steeper and more linear restoring torque progression over the rotation angle range.

Inventive Principle:
Principle #4Asymmetry

2Force

If high preload is applied to increase restoring torque, then the torque magnitude improves, but the elastomer body experiences non-linear stress distribution leading to increased wear and reduced service life

Engineering Contradiction:
Improverestoring torque magnitudeVSAvoidservice life
Core Design Contradiction:
ForceVSReliability

Solution Approach 1:

The patent applies local quality by designing the contact surfaces with specific non-circular geometries that create more uniform stress distribution in the elastomer body. This localized geometric optimization ensures that stress is distributed more evenly throughout the elastomer material, reducing peak stresses and non-linear stress concentrations that lead to wear and failure, thereby extending service life while maintaining adequate restoring torque.

Inventive Principle:
Principle #3Local quality

3Ease of operation

If the angle of rotation range is increased, then the seating comfort improves, but the restoring torque becomes highly non-linear

Engineering Contradiction:
Improveseating comfortVSAvoidtorque linearity
Core Design Contradiction:
Ease of operationVSStability of the object's composition

Solution Approach 1:

The patent uses asymmetric non-circular contact surface geometries to achieve a more linear restoring torque characteristic over larger rotation angles. The specific geometry (rectangular, square, or other polygonal shapes) is designed to control the stress distribution pattern in the elastomer body during rotation, resulting in a restoring torque that increases more linearly with angle of rotation, thereby maintaining predictability and comfort over extended rotation ranges.

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 solution provides a seat device with improved seating comfort by maintaining a linear restoring torque curve over a broader angle range, reducing wear on the elastomer body, and extending its service life through optimized stress distribution and reduced preload requirements.

Implementation Method 1

an elastomer body (16) arranged in a space between the inner housing (12) and the outer housing (14)... during the respective rotation the inner housing (12) moves relative to the outer housing (14) and a deformation of the elastomer body (16) is generated, so that the elastomer body (16) generates a restoring torque

Methodology Applied
Scientific EffectElasticity: Elasticity

Implementation Method 2

The contact surface of the inner housing (12) and/or the contact surface of the outer housing (14) are designed in such a way that, when the inner housing (12) and/or the outer housing (14) is/are rotated about the axis of rotation (6), a homogeneous distribution of tensile and compressive stresses within the elastomer body (16) can be achieved

Methodology Applied
Scientific EffectStress distribution:

Data Source

PatentEP2347678B1Seat assembly with an elastomer torsion-spring element
Publication Date: 2013.02.20 STOLL GIROFLEX
  • EP2347678B1 patent drawingFigure 1
  • EP2347678B1 patent drawingFigure 2
  • EP2347678B1 patent drawingFigure 3A

AI summary

The assembly has torsion spring elements (10) and inner housings (12) that are rotated around a rotating angle at a rotational axis during an oscillating motion of rear supports and/or seats and during the rotation motion of the inner housings relative to an outer housing (14). Deformation of elastomer bodies (16) is generated, so that the elastomer bodies are provided between the outer and inner housings. Contact surfaces (12a, 14a) of the inner and outer housings include non-circular cross sections in a sectional panel perpendicular to the rotational axis, respectively.