Washing Drum Electromagnetic Balancing for Low-Noise Spin Cycles

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Solution Overview

Problem

Existing washing machines experience mechanical vibrations and noise due to imbalanced laundry distribution in the drum, leading to mechanical stress and unpleasant noise, which current imbalance compensation devices do not adequately address.

Innovation Solution

A household appliance with a laundry drum equipped with an imbalance compensation device featuring ferromagnetic or permanent magnetic compensation elements and an electromagnet that generates a magnetic holding force, allowing compensating elements to be held in place until a predetermined speed is reached, at which point centrifugal forces overcome the magnetic force, enabling them to move and balance the drum.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Stability of the object's composition

If compensating elements are allowed to move freely to balance the drum at high speeds, then vibrations are reduced, but the elements cause noise and instability at low speeds

Engineering Contradiction:
Improvedrum balance at high speedVSAvoidnoise and instability at low speed
Core Design Contradiction:
Stability of the object's compositionVSObject-affected harmful factors

Solution Approach 1:

The electromagnetic holding system replaces mechanical constraints that would physically restrict the compensating elements. The electromagnet creates a controllable magnetic field that can hold the elements stationary during low-speed operation, eliminating noise and instability issues, while allowing free movement during high-speed operation when the field strength becomes insufficient against centrifugal force.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

2Object-affected harmful factors

If an electromagnetic holding device is added to control compensating elements, then low-speed noise is reduced, but the device complexity increases

Engineering Contradiction:
Improvelow-speed noiseVSAvoidholding device structure
Core Design Contradiction:
Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

While the electromagnet adds a component, it replaces complex mechanical spring systems, linkages, and physical constraints with a simpler electromagnetic field-based solution. The electromagnet can be integrated into the existing housing structure, and its control is achieved through simple electrical switching based on rotational speed detection, overall reducing mechanical complexity despite adding an electromagnetic component.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

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 solution effectively reduces vibrations and noise by allowing compensating elements to automatically release and balance the drum at higher speeds, preventing unwanted movement at lower speeds and reducing resonance-related noise, thus enhancing the operational stability and quietness of the appliance.

Implementation Method 1

The holding device comprises an electromagnet designed to generate a magnetic field that exerts a magnetic holding force between the electromagnet and the magnetic balancing elements

Methodology Applied
Scientific EffectMagnetic field: Magnetic Field

Implementation Method 2

The electromagnet is designed to generate a magnetic field that exerts a magnetic holding force between the electromagnet and the magnetic balancing elements

Methodology Applied
Scientific EffectMagnetic holding force: Magnetism

Implementation Method 3

during supercritical operation of the washing machine, tends to shift to the side opposite the unbalance mass – with respect to the diameter of the washing machine drum – thus creating a counterweight for the unbalance mass and consequently achieving overall equilibrium

Methodology Applied
Scientific EffectCentrifugal force: Centrifugal Force

Data Source

PatentEP3322847B1Household appliance for caring for pieces of laundry having an imbalance compensation device having an electromagnet and method for operating such a household appliance
Publication Date: 2019.04.17 BSH HAUSGERATE GMBH
  • EP3322847B1 patent drawingFigure 1~2
  • EP3322847B1 patent drawingFigure 3~4
  • EP3322847B1 patent drawingFigure 5~6

AI summary

The invention relates to a household appliance (1) for caring for pieces of laundry (31), having at least one washing drum (3) for receiving pieces of laundry (31) and having at least one imbalance compensation device (13 and 14), which is arranged on the washing drum (3), and which has a housing (18, 21), in which a plurality of compensation elements (20, 23, 27, 29, 32 and 33) are movably contained, wherein at least some compensation elements (20, 23, 27 and 29) are ferromagnetic or permanent magnetic and the imbalance compensation device (13 and 14) comprises at least one holding apparatus (26 and 30) rotationally coupled to the washing drum (3), wherein the holding apparatus (26 and 30) comprises an electromagnet (42) which is designed to generate a magnetic field, which effects a magnetic holding force between the electromagnets (42) and the magnetic compensation elements (20, 23, 27 and 29). The invention also relates to a method for operating a household appliance (1).