Vehicle Seat Backrest Adjustment Mechanism with Constant Tension Spring

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Solution Overview

Problem

Existing vehicle seat backrest inclination adjustment mechanisms require significant force to pivot the backrest, especially when adjusting the backrest backwards, due to the need to change the tension of the spiral spring, which can be cumbersome and inefficient.

Innovation Solution

Incorporating an adapter element with stop elements that interact with the spiral spring ends to manage the tension, allowing the backrest to pivot forward without additional force by maintaining constant tension and requiring increased force only when pivoting backwards, thus simplifying the adjustment process.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a coil spring is used to provide tension during backrest adjustment, then the backrest can be held at adjusted positions, but significant force is required to pivot the backrest especially when adjusting backwards

Engineering Contradiction:
Improvebackrest position holdingVSAvoidforce required for backrest pivoting
Core Design Contradiction:
ReliabilityVSForce

Solution Approach 1:

The adjustment range is segmented into two distinct zones: a first adjustment range where the coil spring maintains constant tension and requires minimal force, and a second adjustment range where the stop element engages to provide mechanical blocking and require increased force. This segmentation allows the system to optimize force requirements for different adjustment scenarios.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The system dynamically transitions between two operational states based on the backrest angle: in the first state (first adjustment range), the coil spring provides continuous tension; in the second state (second adjustment range), the stop element provides rigid mechanical support. This dynamic switching optimizes the force characteristics for each adjustment phase.

Inventive Principle:
Principle #15Dynamics

2Adaptability or versatility

If the coil spring tension is changed during backrest adjustment, then the backrest can be positioned at different angles, but this requires additional force and complicates the adjustment process

Engineering Contradiction:
Improvebackrest angle positioningVSAvoidadjustment process simplicity
Core Design Contradiction:
Adaptability or versatilityVSEase of operation

Solution Approach 1:

The adjustment process is segmented into two distinct phases with different force characteristics. The first phase allows free adjustment with constant spring tension, while the second phase engages the stop element for rigid positioning. This segmentation simplifies operation by eliminating the need to continuously adjust spring tension throughout the entire range.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The stop element acts as an intermediary mechanism that transitions the system from spring-based tension to rigid mechanical blocking. This intermediary allows the backrest to move freely within the first adjustment range while providing stable positioning in the second range, simplifying the overall adjustment process.

Inventive Principle:
Principle #24Intermediary (Mediator)

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

Enables effortless forward adjustment of the backrest without additional force while ensuring that more force is required for backward adjustment, improving user convenience and reducing the effort needed for backrest positioning.

Implementation Method 1

a coil spring of the device is connected on one side to the tilt adjustment device and on the other side to the seat part

Methodology Applied
Scientific EffectElasticity: Elasticity

Data Source

PatentEP3287313B1Device for adjusting a backrest incline
Publication Date: 2019.12.04 GRAMMER AG
  • EP3287313B1 patent drawingFigure 1A~1C
  • EP3287313B1 patent drawingFigure 2~3
  • EP3287313B1 patent drawingFigure 4~5A

AI summary

Device for a vehicle seat for adjusting the backrest inclination of a backrest extending in a longitudinal direction relative to a seat section, wherein a tilt adjustment device of the device for adjusting the backrest inclination, rotatable about a first axis of rotation extending in the direction of the width of the vehicle seat, is connected to the seat section, and a coil spring of the device is connected on one side to the tilt adjustment device and on the other side to the seat section, wherein the device comprises the tilt adjustment device, an adapter element rotatable about the first axis of rotation which is fixedly connected to the tilt adjustment device and has a first stop element, a coil spring rotatable about the first axis of rotation with a first coil spring end and a second coil spring end arranged fixed relative to the adapter element, and a second stop element which is fixedly connected to the seat section.and wherein, at a first angle between the longitudinal direction of the backrest and a longitudinal direction of the vehicle seat, the second end of the coil spring is in effective contact with the first stop element, and at a first angle, with the second stop element, it is in effective contact with the first stop element.