Polymeric Bearing Assembly for Washing Tub Rust Prevention
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Solution Overview
Problem
Bearing assemblies for washing machine drums face issues due to metallic spacers forming ferrous oxides (rust) from water vapor and condensate, despite being protected from direct contact with liquids.
Innovation Solution
A bearing assembly with a polymeric housing and spacer, co-molded with the washing machine tub, featuring a box-type spacer structure and annular rim for enhanced stiffness and sealing, using polymeric materials like polypropylene reinforced with glass fibers to prevent rust formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a metallic spacer is used in the bearing assembly, then the structural strength and stiffness are improved, but ferrous oxides (rust) form on the spacer due to water vapor and condensate
Solution Approach 1:
The patent changes the material parameter of the spacer from metallic to polymeric material. This fundamental material substitution eliminates the chemical reactivity that causes rust formation while maintaining the structural function of the spacer through appropriate polymer selection and reinforcement
Solution Approach 2:
The patent employs composite polymeric materials, specifically polypropylene reinforced with glass fibers, to create a spacer that combines the corrosion resistance of polymers with the structural strength traditionally provided by metal. The glass fiber reinforcement provides the necessary mechanical properties while the polymeric matrix prevents rust formation
2Productivity
If the bearing assembly is co-molded with the tub, then the assembly operations are facilitated and production time is reduced, but the stiffness and mechanical strength may be compromised
Solution Approach 1:
The patent merges the bearing assembly with the tub through co-molding, creating an integral structure that reduces assembly operations and production time. The polymeric housing is molded directly onto the tub, eliminating separate assembly steps while maintaining structural integrity
Solution Approach 2:
The use of reinforced polymeric materials (polypropylene with glass fibers) in the co-molded housing ensures that the integrated structure maintains adequate mechanical strength and stiffness despite being formed as a single piece with the tub
3Object-generated harmful factors
If a polymeric spacer is used instead of metallic, then rust formation is prevented, but the stiffness and structural strength may be reduced
Solution Approach 1:
The patent uses composite polymeric materials, specifically polypropylene reinforced with glass fibers, to create a spacer that combines the corrosion resistance of polymers with the structural strength traditionally provided by metal. The glass fiber reinforcement provides the necessary mechanical properties while the polymeric matrix prevents rust formation
Solution Approach 2:
The patent modifies the material parameters of the polymeric spacer through reinforcement with glass fibers, changing its mechanical properties to achieve the required structural strength and stiffness while maintaining the rust-prevention benefits of polymeric material
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 reduces production costs and time, enhances the reliability of the watertight seal, and provides improved stiffness and resistance to mechanical, vibrational, and thermal stresses while preventing rust formation.
Implementation Method 1
a polymeric housing (50). The housing includes a box-type frame molded to the bearings and to the spacer and configured to provide stiffness to the bearing assembly
Data Source
AI summary
A bearing assembly is for a washing machine, the washing machine including a tub and a drum rotatable about a central axis. The bearing assembly comprises two bearings spaced axially apart along the central axis, a spacer disposed generally between the two bearings, and a polymeric housing. The housing includes a box-type frame molded to the bearings and to the spacer and configured to provide stiffness to the bearing assembly.