Body Support Structure With Weight-Sensing Recline Spring Adjustment

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Solution Overview

Problem

Existing body support structures for sitting furniture, such as chairs, struggle to accurately and quickly adapt the spring mechanism to the weight of a person, leading to sluggish and inaccurate adjustments due to the dissipation of weight forces from backrests and armrests, and are often costly to produce.

Innovation Solution

A body support structure with a weighing mechanism that includes a leaf spring and a support system, where the leaf spring is prestressed to allow smooth movement and is only engaged when the person reclines, providing a responsive and adjustable reaction force based on the person's weight, and a movement converter that converts weighing movements into displacement movements to adjust the spring mechanism effectively.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a spring mechanism is compressed by the weight force of a person to automatically adjust the backrest inclination, then the spring mechanism adapts to the person's weight, but weight forces from backrests and armrests are dissipated through the carrier coupling, resulting in too weak a reaction force

Engineering Contradiction:
Improveadaptation of spring mechanism to person's weightVSAvoidreaction force of the carrier of the back part
Core Design Contradiction:
Adaptability or versatilityVSForce

Solution Approach 1:

The weighing mechanism is segmented into separate components: a first spring element for weighing, a second spring element for supporting the seat, and a movement converter. This segmentation isolates the weighing function from the backrest carrier, preventing force dissipation and ensuring sufficient reaction force for reclining support.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

A movement converter acts as an intermediary between the weighing mechanism and the backrest carrier. It translates the weighing movement into a displacement that adjusts the second spring element, thereby controlling the reaction force without directly coupling the weighing function to the carrier.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Measurement precision

If weighing of a user takes place under load to adjust the leaf spring, then the weighing mechanism can detect weight, but the adjustment process becomes sluggish and slow and inaccurate

Engineering Contradiction:
Improveaccuracy of weight detectionVSAvoidspeed of weighing and adjustment
Core Design Contradiction:
Measurement precisionVSSpeed

Solution Approach 1:

The first spring element is pre-tensioned between the support and the seat before the user sits down. This preliminary action allows the weighing mechanism to be ready to detect weight changes immediately, eliminating the sluggishness associated with adjusting under full load and enabling faster, more accurate measurements.

Inventive Principle:
Principle #10Preliminary action

3Ease of operation

If the leaf spring is prestressed to allow smooth movement, then the reclining experience becomes smooth and sensitive, but the spring mechanism may not engage properly when the person reclines

Engineering Contradiction:
Improvesmoothness of reclining movementVSAvoidengagement of spring mechanism during reclining
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

The support is designed to move dynamically along a curved path as the user reclines, maintaining optimal contact with the first spring element. This dynamic adjustment ensures that the prestressed spring element remains engaged and provides reliable support throughout the reclining motion, preventing disengagement while maintaining smooth operation.

Inventive Principle:
Principle #15Dynamics

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 ensures a responsive and accurate adjustment of the spring mechanism to the person's weight, providing a smooth and sensitive reclining experience while maintaining cost-effectiveness by effectively detecting and adapting to the weight forces from all parts of the body, including backrests and armrests.

Implementation Method 1

A body support structure with a weighing mechanism that includes a leaf spring and a support system, where the leaf spring is prestressed to allow smooth movement and is only engaged when the person reclines

Methodology Applied
Scientific EffectElasticity: Elasticity

Implementation Method 2

The upper part is supported against the middle part by means of a second spring element

Methodology Applied
Scientific EffectSpring force: Spring

Data Source

PatentEP2001338B1Body support structure
Publication Date: 2016.10.26 HERMAN MILLER INC
  • EP2001338B1 patent drawingFigure 1a~1b
  • EP2001338B1 patent drawingFigure 1c~1d
  • EP2001338B1 patent drawingFigure 1e~1h

AI summary

The invention relates to a body support structure (1), such as a piece of furniture (1), in particular a piece of furniture for sitting on or a piece of furniture for lying on, such as, for example, chair (3), armchair, stool, bed or sofa, a seat (7) of the piece of furniture (1) being supported by a spring mechanism (SM), and the spring mechanism (SM) being capable of being set to a weight force (40) with which a person acts on the seat (7).