Washer-Dryer Drum Ventilation Speed for Faster Drying

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Solution Overview

Problem

Combined clothes washing and drying machines face inefficiencies in the drying cycle due to the limited inner volume of the rotating drum and the radial flow of hot air, which leads to longer drying times and increased energy usage, as the hot air primarily affects the surface of the clothes rather than being evenly distributed throughout the load.

Innovation Solution

Increasing the rotational speed of the drum during the drying cycle to a 'ventilation speed' that lifts the clothes off the bottom, allowing hot air to flow axially and radially through the clothes, and adjusting the speed based on the degree of moisture in the clothes to optimize drying efficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If the drum rotates at conventional speeds during drying, then the clothes remain on the bottom of the drum, but the hot air flow is restricted and drying efficiency is reduced

Engineering Contradiction:
Improvedrying efficiencyVSAvoiddrum rotational speed
Core Design Contradiction:
ProductivityVSSpeed

Solution Approach 1:

The drum rotational speed is dynamically adjusted during the drying cycle. The control unit varies the rotational speed between a first value (clothes on bottom) and a second higher value (clothes distributed on inner surface), optimizing drying efficiency at different stages of the drying process

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The drum rotational speed is periodically varied during the drying cycle, alternating between lower and higher speeds to repeatedly redistribute the clothes and maintain efficient hot air flow through the load

Inventive Principle:
Principle #19Periodic action

2Productivity

If the drum rotates at high speed continuously, then clothes are distributed on the inner surface improving air flow, but washing performance deteriorates due to reduced tumbling action

Engineering Contradiction:
Improvedrying efficiencyVSAvoidwashing performance
Core Design Contradiction:
ProductivityVSManufacturing precision

Solution Approach 1:

The drum rotational speed is periodically varied during the drying cycle, alternating between lower and higher speeds to repeatedly redistribute the clothes and maintain efficient hot air flow through the load

Inventive Principle:
Principle #19Periodic action

Solution Approach 2:

The drum rotational speed is dynamically adjusted during the drying cycle. The control unit varies the rotational speed between a first value (clothes on bottom) and a second higher value (clothes distributed on inner surface), optimizing drying efficiency at different stages of the drying process

Inventive Principle:
Principle #15Dynamics

3Loss of time

If conventional drying methods are used, then the machine structure remains simple, but drying time is extended and energy consumption increases

Engineering Contradiction:
Improvedrying timeVSAvoidenergy consumption
Core Design Contradiction:
Loss of timeVSUse of energy by moving object

Solution Approach 1:

A sensor detects the degree of moisture in the clothes and provides feedback to the control unit, which adjusts the drum rotational speed accordingly to optimize drying efficiency and reduce energy consumption

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The drum rotational speed parameter is changed based on moisture detection, varying between different speed values during the drying cycle to optimize the balance between drying efficiency and energy consumption

Inventive Principle:
Principle #35Parameter changes

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

This method enhances moisture removal, reduces drying time, and lowers energy consumption by ensuring hot air passes directly through the clothes, improving the overall performance and energy efficiency of the drying cycle.

Implementation Method 1

the drum (1) is driven to rotate at a speed which is higher than a usual one, in such manner that the washload is substantially lifted off the bottom of the drum and distributed therewithin, thereby spreading out - due to the effect of the centrifugal force - over the entire inner cylindrical surface of the same drum

Methodology Applied
Scientific EffectCentrifugal force: Centrifugal Force

Implementation Method 2

allowing hot air to flow axially and radially through the clothes

Methodology Applied
Scientific EffectConvection: Convection

Implementation Method 3

a heating means for heating the air dehumidified by said dehumidifying means

Methodology Applied
Scientific EffectHeating: Heating

Implementation Method 4

a dehumidifying means for dehumidifying the air inside the circulating passage by cooling the air using cooling water

Methodology Applied
Scientific EffectCooling: Cooling

Data Source

PatentEP2075362B1Improvements in a clothes washing and drying machine
Publication Date: 2015.11.04 ELECTROLUX HOME PROD CORP NV
  • EP2075362B1 patent drawingFigure 1
  • EP2075362B1 patent drawingFigure 2~7
  • EP2075362B1 patent drawingFigure 3~6d

AI summary

Combined clothes washing and drying machine comprising a tub (2) provided with a substantially cylindrical wall, a rotating drum (1) mounted rotatably within it and provided with a number of perforations (6) in the cylindrical side surface thereof, a conduit (3) for exhausting or circulating the drying air as provided with a suction mouth (4) for taking in the air from the interior of said tub (2), said intake mouth (4) being situated on a portion of said substantially cylindrical wall, wherein during at least a definite interval of the drying phase, said drum (1) is driven to rotate at a ventilation speed that is sufficient to cause the washload to distribute on the inner drum surface wall, and contact therewith. Preferably said definite interval is provided at the beginning of the drying phase, and said distribution speed is variable.