Braking Device with Temperature-Compensating Flow Geometry

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Solution Overview

Problem

Braking devices in furniture and household appliances experience undesirable variations in braking properties due to temperature-dependent viscosity of viscous liquids, limiting their effectiveness to a narrow temperature range.

Innovation Solution

A braking device with a temperature-dependent geometry in the flow section, utilizing a bimetallic valve plate that changes shape with temperature to adjust flow resistance, ensuring consistent braking performance across a wide temperature range.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a viscous liquid is used for braking, then braking effect is achieved, but braking properties vary strongly with temperature

Engineering Contradiction:
Improvebraking propertiesVSAvoidtemperature range
Core Design Contradiction:
ReliabilityVSTemperature

Solution Approach 1:

The patent changes the geometric parameters of the flow channel (cross-sectional area, shape) as a function of temperature to compensate for viscosity changes. The flow channel geometry is designed such that at different temperatures, the effective flow area adjusts to maintain constant braking force despite viscosity variations.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent utilizes thermal expansion of the flow channel structure itself. As temperature changes, the flow channel dimensions expand or contract, automatically adjusting the flow resistance to compensate for viscosity changes in the viscous liquid, thereby maintaining consistent braking properties across temperature ranges.

Inventive Principle:
Principle #37Thermal expansion

2Reliability

If valve flaps are arranged inside the piston for temperature-dependent control, then damping effect is adjusted, but structure becomes mechanically complex

Engineering Contradiction:
Improvetemperature-dependent controlVSAvoidstructure
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent extracts the temperature-dependent control function from complex mechanical valve mechanisms and implements it through the inherent thermal expansion properties of the flow channel structure itself, eliminating the need for separate valve flaps and control mechanisms inside the piston.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The flow channel structure performs self-regulation of the braking effect through its own thermal expansion and contraction in response to temperature changes, without requiring external control systems or complex internal valve mechanisms.

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 solution maintains almost constant braking properties from -30°C to +70°C by compensating for viscosity changes, ensuring reliable operation regardless of temperature fluctuations.

Implementation Method 1

utilizing a bimetallic valve plate that changes shape with temperature to adjust flow resistance

Methodology Applied
Scientific EffectBimetallic effect: Bi-Metallic Strip

Implementation Method 2

a viscous liquid braking a movement of the movable element in at least one flow section

Methodology Applied
Scientific EffectViscous damping: Viscous Damping

Data Source

PatentEP3577296B1Braking device and piece of furniture or domestic appliance having a braking device
Publication Date: 2020.12.09 DRUCK & SPRITZGUSSWERK HETTICH
  • EP3577296B1 patent drawingFigure 1a~1c
  • EP3577296B1 patent drawingFigure 2a~2c
  • EP3577296B1 patent drawingFigure 3a~3c

AI summary

The invention relates to a braking device of a piece of furniture or domestic appliance for braking a movable part of the piece of furniture or domestic appliance, having a housing, which is filled with a viscous liquid, and having an element that can be moved in the housing. The viscous liquid brakes motion of the movable element in at least one flow section. The braking device is characterized in that the geometry of the at least one flow section changes with the ambient temperature. The invention further relates to a piece of furniture or a domestic appliance having at least one braking device for braking motion of a movable part of the piece of furniture or domestic appliance.