Sofa Seat Stretching Mechanism with Hinge-Controlled Speed Reduction

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Solution Overview

Problem

Existing sofa seat mechanisms experience sudden weightlessness during transitions and are prone to sticking during state changes, lacking smoothness and stability.

Innovation Solution

A sofa seat stretching device with synchronized stretching assemblies driven by a linear drive unit, featuring stopper members and hinge configurations that reduce transition speed and enhance stability across sitting, TV, and lying positions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If the switching speed is increased to improve operational efficiency, then the transition between positions becomes faster, but the user experiences sudden weightlessness and the mechanism is prone to sticking

Engineering Contradiction:
Improveswitching speedVSAvoidtransition smoothness
Core Design Contradiction:
ProductivityVSReliability

Solution Approach 1:

The patent implements a multi-stage switching process with different speed phases. The mechanism transitions through multiple position states (sitting, reclining, lying) with controlled acceleration and deceleration phases. The driving assembly adjusts speed dynamically during transitions, using periodic motion patterns to ensure smooth acceleration into motion and controlled deceleration before stopping, eliminating sudden weightlessness while maintaining efficient overall transition time

Inventive Principle:
Principle #19Periodic action

Solution Approach 2:

The patent employs dynamic speed control where the driving assembly automatically adjusts its operating speed based on the transition phase. During acceleration phases, speed is gradually increased; during deceleration phases, speed is progressively reduced. This dynamic adjustment prevents abrupt motion changes that cause weightlessness and reduces the likelihood of the mechanism getting stuck during position transitions

Inventive Principle:
Principle #15Dynamics

2Reliability

If the switching speed is decreased to improve transition smoothness, then the user experiences less weightlessness, but the switching process takes longer time

Engineering Contradiction:
Improvetransition smoothnessVSAvoidswitching time
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

The patent uses periodic motion with optimized cycle timing. Each transition between positions follows a standardized time pattern with acceleration, constant velocity, and deceleration phases. This periodic approach ensures that smooth transitions are achieved without unnecessarily extending the total switching time, as the motion profile is optimized to complete transitions efficiently while maintaining comfort

Inventive Principle:
Principle #19Periodic action

Solution Approach 2:

The driving assembly dynamically adjusts speed based on real-time position feedback and transition phase. During phases requiring smoothness (acceleration and deceleration), speed is controlled at lower rates; during mid-transition phases where smoothness is less critical, speed increases to reduce overall switching time. This dynamic optimization balances transition smoothness with time efficiency

Inventive Principle:
Principle #15Dynamics

3Ease of operation

If the mechanical stretching device is equipped with electric driving assembly to improve operational convenience, then the stretching operation becomes easier, but the device complexity increases

Engineering Contradiction:
Improveoperational convenienceVSAvoiddevice complexity
Core Design Contradiction:
Ease of operationVSDevice complexity

Solution Approach 1:

The electric driving assembly is equipped with control systems that automatically manage the stretching and retracting operations. The system self-regulates speed, position, and timing without requiring manual intervention for each adjustment. This automation provides operational convenience while the control system is integrated into the existing mechanical structure, minimizing the increase in overall device complexity

Inventive Principle:
Principle #25Self-service

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 device ensures smooth transitions between positions, reduces weightlessness, and maintains stability, providing a comfortable zero-gravity feel and ergonomic support.

Implementation Method 1

the mechanical stretching device is usually equipped with an electric driving assembly which is used for push the mechanical stretching device to stretch or retract

Methodology Applied
Scientific EffectLinear motor effect: Linear Motor

Implementation Method 2

two ends of each seat frame unit are hinged to one end of one backrest unit and one end of one leg stretching unit respectively

Methodology Applied
Scientific EffectHinge mechanism: Hinge

Data Source

PatentEP4183295B1Sofa seat stretching device
Publication Date: 2025.07.09 DEWERTOKIN TECHNOLOGY GROUP CO LTD
  • EP4183295B1 patent drawingFigure 1~2
  • EP4183295B1 patent drawingFigure 3~4
  • EP4183295B1 patent drawingFigure 5~6

AI summary

Embodiments of the present disclosure relates to the field of furniture. Provided is a sofa seat stretching device. In the sofa seat stretching device, one end of a second support facing away from a first support, and a second leg rest plate connector are hinged at a fourth hinge point, so that the stretching assembly's stretching speed is reduced in a process of switching from a sitting position state to a lying position state when a driving assembly acts in the same way, and the weightlessness feeling can be effectively avoided. Moreover, the driving assembly drives the stretching assembly so that the process of switching the stretching assembly from the lying position state to the sitting position state is smoother.