Dual-Drum Washing Machine for 3D Laundry Motion Control

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Solution Overview

Problem

Conventional washing machines limit laundry motion to two-dimensional circumferential motion within the drum, leading to inefficient washing, increased washing time, and potential entanglement issues, which result in wrinkles and difficulty in removing laundry.

Innovation Solution

A dual-drum washing machine design with independently rotating main and sub drums, driven by a single dual-motor system, allowing three-dimensional motion of laundry through differential rotation speeds and directions, and optimized torque distribution to enhance washing efficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If a single drum is rotated to move the laundry, then the structure is simple, but the laundry motion is limited to two-dimensional circumferential motion without axial-direction motion

Engineering Contradiction:
Improvedrum structureVSAvoidlaundry motion capability
Core Design Contradiction:
Device complexityVSAdaptability or versatility

Solution Approach 1:

The inner drum is nested inside the outer drum, with the inner drum rotating on an inner shaft and the outer drum rotating on an outer shaft. This nested configuration allows both drums to rotate independently in different directions, enabling three-dimensional laundry motion (circumferential motion from outer drum rotation and axial motion from inner drum rotation) without significantly increasing overall structural complexity.

Inventive Principle:
Principle #7Nested doll (Nesting)

Solution Approach 2:

The invention transitions from two-dimensional circumferential motion (single drum) to three-dimensional motion by adding the inner drum that rotates in a different dimension. The inner drum's rotation around its own axis, while nested within the outer drum, creates axial-direction motion components that complement the outer drum's circumferential motion, achieving comprehensive 3D laundry movement.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

2Device complexity

If a single drum is used, then the device complexity is low, but the washing efficiency is limited and washing time increases

Engineering Contradiction:
Improvedrum configurationVSAvoidwashing efficiency
Core Design Contradiction:
Device complexityVSProductivity

Solution Approach 1:

The nested dual-drum configuration allows both drums to operate simultaneously with different rotation patterns. The outer drum provides circumferential motion while the inner drum provides axial motion, creating more varied laundry movement paths that improve washing efficiency without requiring a completely separate second drum, thus balancing complexity and productivity.

Inventive Principle:
Principle #7Nested doll (Nesting)

Solution Approach 2:

The invention employs dynamic rotation control where the inner and outer drums can rotate at different speeds and directions. This dynamic operation creates varied motion patterns that enhance washing efficiency by preventing laundry from settling in fixed positions, while the shared motor and nested structure keep the overall system complexity manageable.

Inventive Principle:
Principle #15Dynamics

3Speed

If high-speed rotation is used for dehydration, then dehydration efficiency is improved, but laundry becomes entangled and stuck on the drum surface

Engineering Contradiction:
Improvedrum rotation speedVSAvoidlaundry entanglement
Core Design Contradiction:
SpeedVSObject-generated harmful factors

Solution Approach 1:

During the dehydration phase, the invention utilizes differential rotation between the inner and outer drums to prevent laundry entanglement. While the outer drum rotates at high speed for centrifugal dehydration, the inner drum rotates at a different speed or in the opposite direction, creating relative motion that continuously disturbs the laundry and prevents it from adhering to the drum surface, thereby reducing wrinkles and entanglement.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The system applies preliminary anti-action by using the inner drum's counter-rotation or differential rotation to counteract the centrifugal force that causes laundry to stick to the outer drum surface during high-speed dehydration. This opposing motion prevents the harmful effect of entanglement before it fully develops.

Inventive Principle:
Principle #9Preliminary anti-action

4Device complexity

If circumferential motion only is provided, then the drum structure is simple, but the physical force applied to laundry is insufficient for effective washing

Engineering Contradiction:
Improvemotion mechanismVSAvoidphysical force on laundry
Core Design Contradiction:
Device complexityVSForce

Solution Approach 1:

The nested dual-drum structure enables the inner drum to rotate independently within the outer drum, creating axial-direction motion components in addition to the outer drum's circumferential motion. This configuration generates more varied and intense physical forces on the laundry through combined rotational movements, improving washing effectiveness without requiring a completely complex multi-mechanism system.

Inventive Principle:
Principle #7Nested doll (Nesting)

Solution Approach 2:

By adding the inner drum that rotates around a different axis, the system introduces motion in another dimension (axial direction) beyond the outer drum's circumferential motion. This dimensional addition creates more complex laundry trajectories and increases the physical forces applied to the laundry through varied motion patterns, enhancing washing effectiveness.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

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 dual-drum design improves washing performance by enabling three-dimensional laundry motion, reducing washing time, preventing entanglement, and facilitating easy laundry removal, while minimizing material waste and motor size.

Implementation Method 1

the rotor teeth form magnetic fluxes with the stator so as for the rotor to have a rotational force

Methodology Applied
Scientific EffectElectromagnetic induction: Electromagnetic Induction

Implementation Method 2

a rotor rotating about a rotor shaft, including rotor teeth, a permanent magnet and a bushing

Methodology Applied
Scientific EffectMagnetism: Magnetism

Implementation Method 3

The laundry is rotated along the inner circumferential surface of the drum by a centrifugal force responsive to the rotation of the drum

Methodology Applied
Scientific EffectCentrifugal force: Centrifugal Force

Implementation Method 4

a falling motion from an upper side of the drum by the force of gravity

Methodology Applied
Scientific EffectGravity: Gravitation

Implementation Method 5

a frictional force generated between the drum, which is rotated by a driving force transferred from a driving motor, and the laundry

Methodology Applied
Scientific EffectFriction: Friction

Data Source

PatentEP2771964B1Washing machine
Publication Date: 2018.02.28 LG ELECTRONICS INC
  • EP2771964B1 patent drawingFigure 1~2
  • EP2771964B1 patent drawingFigure 3~4
  • EP2771964B1 patent drawingFigure 5~6

AI summary

Disclosed is a permanent magnet motor for a washing machine. The permanent magnet motor comprises a stator including stator teeth and stator slots, a stator coil being wound on the stator teeth, and a rotor rotating about a rotor shaft, including rotor teeth, a permanent magnet and a bushing, the rotor being spaced from an inner circumference of the stator.