Synchronous seat adjustment

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Solution Overview

Problem

Existing chair designs with synchronous adjustment between backrest and seat inclination lack efficient material usage, productive assembly, ease of maintenance, and aesthetic design while providing optimal ergonomic functionality.

Innovation Solution

A chair design featuring independently articulated backrest brackets with elastic deformation, supported by adjustable spring units and a height-adjustable gas spring, allowing for synchronized back and seat inclination adjustment from zero to maximum positions with minimal maintenance and efficient assembly.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If synchronous adjustment mechanism is implemented, then ergonomic functionality is improved, but device complexity increases

Engineering Contradiction:
Improveergonomic functionalityVSAvoiddevice complexity
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The backrest is divided into multiple independently adjustable segments (upper backrest, lower backrest, headrest) that can be adjusted separately. This segmentation allows the complex ergonomic adjustment function to be broken down into simpler, independent adjustment mechanisms, making the overall system more manageable despite its versatility.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The chair employs dynamic adjustment mechanisms including height-adjustable gas spring, tilt tension adjustment, and multi-position locking systems. These dynamic elements allow the chair to adapt to different user preferences and positions, providing ergonomic functionality through controlled movement and adjustment capabilities.

Inventive Principle:
Principle #15Dynamics

2Manufacturing precision

If multiple spring units are used for adjustment, then adjustment precision is improved, but manufacturing complexity increases

Engineering Contradiction:
Improveadjustment precisionVSAvoidmanufacturing complexity
Core Design Contradiction:
Manufacturing precisionVSEase of manufacture

Solution Approach 1:

The adjustment mechanism is segmented into multiple spring units (first spring unit, second spring unit, third spring unit) each responsible for specific adjustment functions. This segmentation allows for precise control of different movement aspects while enabling modular manufacturing and assembly of each spring unit independently.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The spring units are designed with adjustable parameters including spring constant, pre-load, and free length. These parameter changes allow precise adjustment of the chair's mechanical behavior without requiring complex manufacturing processes, as the precision is achieved through adjustable parameters rather than tight manufacturing tolerances.

Inventive Principle:
Principle #35Parameter changes

3Adaptability or versatility

If independent backrest arms are implemented, then ergonomic support is improved, but material usage increases

Engineering Contradiction:
Improveergonomic supportVSAvoidmaterial usage
Core Design Contradiction:
Adaptability or versatilityVSQuantity of substance

Solution Approach 1:

The backrest structure is segmented into two independent backrest arms (first backrest arm, second backrest arm) that can move independently. This segmentation provides improved ergonomic support by allowing asymmetric adjustment for each side, while the arms share common mounting points and structural elements to minimize overall material usage.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The backrest arms are designed as multi-functional components that provide both structural support and adjustment functionality. They serve multiple purposes: supporting the backrest, enabling independent movement, providing mounting points for springs, and acting as leverage arms for adjustment mechanisms, thereby reducing the need for separate components and minimizing material usage.

Inventive Principle:
Principle #6Universality (Multi-functionality)

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 provides enhanced ergonomic support, efficient material usage, and ease of maintenance while ensuring optimal ergonomic functionality through synchronized back and seat inclination adjustments, supporting user comfort and aesthetic appeal.

Implementation Method 1

a height-adjustable gas spring is arranged in the base, upon which the base rests, allowing the seat support to be adjusted to a user-friendly height

Methodology Applied
Scientific EffectGas spring: Spring

Implementation Method 2

The back of the seat support is elastically torsionally flexible

Methodology Applied
Scientific EffectElastic torsional flexibility: Elasticity

Implementation Method 3

A first spring unit is provided on the chair, which acts against the respective movable backrest bracket. A second spring unit is connected in parallel to the first spring unit

Methodology Applied
Scientific EffectSpring: Spring

Data Source

PatentEP2908696B2Synchronous seat adjustment
Publication Date: 2023.03.15 VITRA
  • EP2908696B2 patent drawingFigure 1A
  • EP2908696B2 patent drawingFigure 1B
  • EP2908696B2 patent drawingFigure 1C

AI summary

Disclosed is a type of seat with relative synchronous displacement between back incline and seat incline, specifically along a region between a respective zero position of back incline (R0) and seat incline (S0) and a respective maximum back incline and seat incline. The seat has an underframe (1) which is intended to be placed on the floor and on which a base (2) is rigidly secured. A seat support (6) is connected to the base (2) and has a seat region and a back region. The seat also comprises two backrest frames (3) which can be extended separately towards each other and which are secured at one side on the base (2) and at another side on the back region of the seat support (6). The two backrest frames (3) are attached independently of each other on the base (2) on a stationary first axis of rotation (D1). The seat region of the seat support (6) is attached on the base (2) on a stationary second axis of rotation (D2). The two backrest frames (3) are attached independently of each other on the back region of the seat support (6) on an elastically deformable third axis of rotation (D3). The back region of the seat support (6) is elastically twistable. A cover is stretched over the seat support. In the embodiment as a rotating office seat, a height-adjustable gas spring (12) is arranged in the underframe (1), on which gas spring the base (2) rests, in order to set the seat support (6) at a height which corresponds to the needs of a user and in order to design a vertical axis (V) in rotatable manner.