Plastic Dishwasher Frame Joint to Prevent Crevice Corrosion

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Solution Overview

Problem

Conventional dishwashers face high production costs due to the use of expensive chromium-nickel steel for corrosion resistance, and crevice corrosion issues arise when welding ordinary chromium steel with chromium-nickel steel, particularly at seam regions and in areas exposed to moisture.

Innovation Solution

A two-part container casing design where the frame part, made of plastic, is form-fitted or materially bonded to the container casing and rear wall, made of ordinary steel, with a sealing element preventing crevice corrosion by sealing the gap between the frame part and container casing, allowing the use of more economical chromium steel for the container hood.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If chromium-nickel steel is used for the container hood, then corrosion resistance is improved, but production cost increases

Engineering Contradiction:

Improvecorrosion resistanceVSAvoidproduction cost

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The container hood is divided into two parts: a front frame part made of plastic and a rear container casing made of chromium steel. This segmentation allows each part to be made from materials optimized for its specific function and exposure conditions, reducing overall cost while maintaining corrosion resistance where needed.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different materials are used for different regions of the container hood based on their corrosion exposure. The front frame part uses plastic where corrosion resistance is needed but full metal construction would be excessive, while the rear container casing uses chromium steel in areas requiring higher structural integrity and corrosion resistance.

Inventive Principle:

Principle #3Local quality

2Ease of manufacture

If ordinary chromium steel is used for the container hood, then production cost is reduced, but crevice corrosion occurs at weld seams

Engineering Contradiction:

Improveproduction costVSAvoidcorrosion resistance at join regions

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

A sealing element acts as an intermediary between the frame part and container casing, filling the gap and preventing crevice corrosion. This allows ordinary chromium steel to be used without the crevice corrosion problem that would otherwise occur at the join between dissimilar metals.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The sealing element is a relatively simple, replaceable component that prevents corrosion at the joint. By using this inexpensive sealing solution, the more expensive chromium-nickel steel can be avoided in favor of cheaper chromium steel, while still protecting against crevice corrosion.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

3Ease of manufacture

If the container casing is made as a single piece, then manufacturing is simplified, but deformation stability during transportation is reduced

Engineering Contradiction:

Improvemanufacturing simplicityVSAvoiddeformation stability

Core Design Contradiction:

Ease of manufactureVSStability of the object's composition

Solution Approach 1:

The container hood is segmented into the frame part and container casing, which are joined together. This segmentation allows the container casing to be made as a single piece for manufacturing simplicity, while the frame part provides additional structural support and stability during transportation.

Inventive Principle:

Principle #1Segmentation

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 design significantly reduces production costs by using ordinary steel for the container hood while preventing corrosion, enhancing stability and simplifying the manufacturing process through injection molding and eliminating the need for separate sealing components.

Implementation Method 1

a sealing element preventing crevice corrosion by sealing the gap between the frame part and container casing

Methodology Applied

Scientific EffectSealing:

Implementation Method 2

simplifying the manufacturing process through injection molding

Methodology Applied

Scientific EffectInjection molding:

Data Source

PatentUS9055856B2Dishwasher with a plastic frame part which is fixed to a treatment container

Publication Date: 2015.06.16 BSH HAUSGERATE GMBH

AI summary

A dishwasher includes a plastic frame that is fixed to a treatment container. The front of the treatment container has a filling opening which can be closed by a door. The treatment container has a container casing, which comprises side walls, a container roof, and the frame. The frame forms a front face of the treatment container and is connected to the container casing in an interlocking manner.