Co-Molded Washing Machine Bushing With Static Charge Dissipation

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Solution Overview

Problem

The introduction of plastic material in co-molded tubular bushings for washing machines has led to electrostatic problems due to electrical insulation, which were not present in metal bushings, causing issues with static electricity accumulation and discharges.

Innovation Solution

A tubular bushing design incorporating metal components for rolling bearings and a dispersion system with conductive elements to prevent static electricity accumulation, featuring a spacer for structural integrity and a plastic sleeve for co-molding, with a conductive path from the drive shaft to earth to dissipate static charges.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If plastic material is used for the containing sleeve in co-molded tubular bushings, then manufacturing complexity and production time are reduced, but electrostatic accumulation and discharges occur

Engineering Contradiction:
Improvemanufacturing complexityVSAvoidelectrostatic accumulation
Core Design Contradiction:
Ease of manufactureVSObject-affected harmful factors

Solution Approach 1:

The patent employs composite material construction by integrating metal components (bearings, drive shaft) within a plastic containing sleeve. This composite structure allows the plastic sleeve to provide ease of manufacture and co-molding capability, while the metal components provide electrical conductivity to prevent electrostatic accumulation. The co-molding process creates a unified structure combining the advantages of both material types.

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The metal bearing components act as intermediary elements that transfer electrical charges from the plastic containing sleeve to the drive shaft, which is connected to earth. This intermediary metal pathway enables the plastic structure to maintain its insulating properties while still allowing electrostatic discharge through the conductive metal components.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Object-affected harmful factors

If metal material is used for tubular bushings, then electrostatic discharge is prevented, but manufacturing complexity and production time increase

Engineering Contradiction:
Improveelectrostatic discharge preventionVSAvoidproduction time
Core Design Contradiction:
Object-affected harmful factorsVSEase of manufacture

Solution Approach 1:

The patent merges the tubular bushing structure with the washing machine tub through co-molding, creating an integrated assembly. The containing sleeve is co-molded with the tub, and the metal bearings are integrated within this structure, eliminating the need for separate assembly steps and reducing production time while maintaining electrostatic discharge prevention capabilities.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The solution uses composite materials where the plastic containing sleeve provides ease of manufacture and co-molding capability, while integrated metal bearing components provide electrical conductivity for electrostatic discharge prevention. This composite approach allows both requirements to be met simultaneously.

Inventive Principle:
Principle #40Composite materials

3Productivity

If co-molding process is used for tubular bushings and tubs, then production efficiency is improved, but electrostatic problems arise due to plastic material insulation

Engineering Contradiction:
Improveproduction efficiencyVSAvoidelectrostatic problems
Core Design Contradiction:
ProductivityVSObject-affected harmful factors

Solution Approach 1:

The co-molded structure incorporates composite materials with the plastic containing sleeve providing the co-molding capability for high production efficiency, while metal bearing components integrated within provide electrical conductivity paths to prevent electrostatic problems. The co-molding process creates a unified structure combining both material types.

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The patent applies local quality by making specific regions of the bushing structure conductive (metal bearings and drive shaft contact points) while maintaining the overall plastic structure for co-molding. This localized conductivity approach allows the majority of the structure to remain plastic for manufacturing efficiency, with only critical areas requiring conductive properties.

Inventive Principle:
Principle #3Local quality

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 effectively prevents electrostatic discharges and accumulation of static electricity within the washing machine while maintaining the production efficiency of co-molded components by ensuring the tubular bushing is both electrically conductive and structurally sound.

Implementation Method 1

a dispersion means (70), for example, a current dispersion device (70), which is incorporated in the containing sleeve (50) and electrically connects both to the drive shaft (15) and to earth, to prevent an accumulation of static electricity in the washing machine and prevent electrostatic discharges

Methodology Applied
Scientific EffectElectrical conduction: Conduction (electrical)

Data Source

PatentEP2853630B1Tubular bushing co-moldable with tubs of washing machines
Publication Date: 2016.04.13 AB SKF SKF PATENT DEPARTMENT
  • EP2853630B1 patent drawingFigure 1~3

AI summary

Tubular bushing (10) co-moldable with tubs of washing machines, the tubular bushing (10) suitable to be engaged by a drive shaft (15) of the washing machine extending along a central axis (A) and being provided with two rolling bearings (20), arranged at a given distance from each other along the axis (A) so as to allow rotation of the drive shaft (15) with respect to the tub (11), and a containing sleeve (50), made of plastic and by means of co-molding around the two bearings (20); a current dispersion means (70) being incorporated in the said containing sleeve (50) and suitable to be electrically connected both to the said drive shaft (15) and to earth so as to prevent an accumulation of static electricity in the washing machine and prevent electrostatic discharges.