Office Chair Spring Adjustment With Curved Track Support

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Solution Overview

Problem

Modern office environments require chairs to be frequently adjusted by different users to accommodate individual needs, but existing chairs are often time-consuming to adjust and may lead to long-term health issues due to inadequate adjustment.

Innovation Solution

A chair with a spring mechanism and adjustment device featuring a curved track and actuator system, allowing for quick and effortless adjustment with a transmission ratio of 1:0.5 to 1:4, and the option for manual or electric drive, including a Bowden cable and gear transmission, enabling easy adaptation to various user weights.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of time

If a traditional adjustment mechanism is used, then the chair structure remains simple, but the adjustment time becomes excessive and user comfort is compromised

Engineering Contradiction:
Improveadjustment timeVSAvoidadjustment device complexity
Core Design Contradiction:
Loss of timeVSDevice complexity

Solution Approach 1:

The patent replaces traditional mechanical adjustment mechanisms with a motor-driven system featuring an actuator and transmission means. The motor (21) drives a transmission mechanism (103) that converts rotational movement into linear displacement of the support (13), enabling rapid adjustment without manual effort while maintaining structural integrity through automated control.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The chair adjustment system operates autonomously through the motor-driven actuator that automatically positions the support without requiring user intervention. The system self-regulates the adjustment process, translating motor rotation into precise support displacement to achieve quick adaptation to different user requirements.

Inventive Principle:
Principle #25Self-service

2Strength

If a heavy-duty spring mechanism is used to support heavy users, then load-bearing capacity is sufficient, but adjustment effort becomes excessive for light users

Engineering Contradiction:
Improveload-bearing capacityVSAvoidadjustment effort
Core Design Contradiction:
StrengthVSEase of operation

Solution Approach 1:

The patent eliminates manual adjustment effort by replacing mechanical lever systems with a motor-driven actuator. The motor (21) provides controlled force to move the support (13) along the track (15) regardless of the spring mechanism's preload, enabling users of any weight to adjust the chair with minimal effort while maintaining adequate load-bearing capacity through the leaf spring (9).

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The system changes the operational parameters of the adjustment mechanism by introducing a motor that can vary its output force and speed. This allows the same adjustment device to handle both light and heavy users effectively, as the motor can adapt its torque and movement rate to match the required adjustment conditions without manual effort.

Inventive Principle:
Principle #35Parameter changes

3Measurement precision

If manual adjustment mechanisms are used, then the device remains simple, but the adjustment precision and speed are insufficient for individual user needs

Engineering Contradiction:
Improveadjustment precisionVSAvoidtransmission means complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent replaces imprecise manual adjustment mechanisms with a motor-driven system featuring a transmission mechanism (103). The motor (21) provides controlled rotational movement that is translated by the transmission means into precise linear displacement of the support (13), enabling accurate positioning at any point along the track (15) for optimal user comfort.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

4Stability of the object's composition

If friction between the support and leaf spring is high, then the support remains stable in position, but the adjustment process becomes difficult and slow

Engineering Contradiction:
Improvesupport position stabilityVSAvoidadjustment ease
Core Design Contradiction:
Stability of the object's compositionVSEase of operation

Solution Approach 1:

The patent overcomes high friction resistance during adjustment by replacing manual mechanical systems with a motor-driven actuator. The motor (21) generates sufficient force to overcome the friction between the support (13) and leaf spring (9) during movement, while the transmission mechanism (103) ensures controlled displacement. Once adjusted, the system maintains stable positioning through the motor's holding capability and the mechanical constraints of the track (15).

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

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 chair can be quickly and easily adjusted to suit different users, minimizing effort and ensuring immediate support, reducing friction and deceleration, and featuring an energy-self-sufficient electric drive that eliminates follow-up costs.

Implementation Method 1

the transmission means comprising a linkage and/or a Bowden cable and/or a gear

Methodology Applied
Scientific EffectMechanical Advantage: Mechanical Advantage

Implementation Method 2

the transmission means comprising a linkage and/or a Bowden cable and/or a gear, with the transmission means being connected to the support and wherein the transmission means is connected to the actuator

Methodology Applied
Scientific EffectGear mechanism: Gear

Implementation Method 3

the track is designed as a curved surface, which is adapted to a curved course of the associated leaf spring in such a way that a movement space formed between the track and an underside of the leaf spring allows the support to move unhindered

Methodology Applied
Scientific EffectFriction reduction: Friction

Implementation Method 4

the spring mechanism being a leaf spring clamped into the base frame on one side and a leaf spring clamped between the leaf spring and the base frame on a roadway movable bearing comprises

Methodology Applied
Scientific EffectElasticity: Elasticity

Data Source

PatentEP3429432B1Chair
Publication Date: 2019.11.20 ZWICK GMBH & CO KG
  • EP3429432B1 patent drawingFigure 1
  • EP3429432B1 patent drawingFigure 2
  • EP3429432B1 patent drawingFigure 3

AI summary

The invention relates to a chair (1) comprising a base frame (2), a seat element (3), a back element (4), a spring mechanism (5) and an adjusting element (6, 101), said spring mechanism (5) comprising a leaf spring (9, 10) tensioned on one side in the base frame (2) and a support (13, 14) which can move between the leaf spring (9, 10) and the base frame (2) on a track (15, 16) and the adjusting element (6, 101) comprises a control element (102) and transfer means (103). The transmission of a movement of the control element (102) into a movement of the support (13, 14) occurs at a transmission ratio of 1:0.5 - 1:4.