Rail pull-out device for a microwave cooking device with an electrically insulating closing element on a rail front side and microwave cooking device

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Solution Overview

Problem

Microwave cooking appliances face issues with electrical discharges between metallic components, leading to component malfunctions, user dissatisfaction, and potential corrosion due to the induction of electrical charges by microwaves, which conventional rail extension devices fail to adequately address.

Innovation Solution

A rail extension device with electrically insulating terminating elements made of ceramic, positioned to maintain a safe distance from the microwave oven door, ensuring electrical insulation and preventing sparks by using a combination of ceramic materials for insulation and conductive materials for the rails, with optional conductive connections for stable contact when necessary.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If conventional metallic rail extension devices are used in microwave cooking appliances, then the rails provide mechanical strength and durability, but electrical discharges and sparks occur between metallic components due to induced electrical charges by microwaves

Engineering Contradiction:
Improvemechanical strength of railsVSAvoidelectrical discharges and sparks
Core Design Contradiction:
StrengthVSObject-affected harmful factors

Solution Approach 1:

The rail extension device is segmented into multiple metallic rails that are electrically insulated from each other by non-conductive intermediate elements (rollers or spacers). This segmentation breaks the continuous conductive path that would otherwise allow electrical discharges to propagate between metallic components.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Electrically non-conductive intermediate elements (rollers or spacers) are introduced as mediators between the metallic rails. These intermediaries prevent direct electrical contact between conductive components, thereby eliminating the harmful electrical discharges and sparks while still allowing mechanical movement.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Volume of moving object

If metallic rails are positioned close to the microwave oven door for compact design, then space is optimized, but the risk of electrical discharges between the rails and door increases

Engineering Contradiction:
Improvespace utilizationVSAvoidelectrical discharges between rails and door
Core Design Contradiction:
Volume of moving objectVSObject-affected harmful factors

Solution Approach 1:

The electrically non-conductive closing element at the front end of the rail acts as an intermediary barrier between the metallic rail and the microwave oven door. This intermediary maintains electrical insulation even when the rail is positioned close to the door, preventing electrical discharges while allowing compact space utilization.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The electrically insulating closing element is pre-installed at the front end of the rail to prevent potential electrical discharges before they can occur. This preliminary protective measure ensures that even when the rail is close to the door, the insulating barrier is already in place to prevent harmful electrical interactions.

Inventive Principle:
Principle #9Preliminary anti-action

3Reliability

If electrically conductive materials are used for the rails, then electrical charges are induced by microwaves, but this creates potential differences and electrical discharges between insulated components

Engineering Contradiction:
Improveelectrical stabilityVSAvoidpotential differences and electrical discharges
Core Design Contradiction:
ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The conductive rail system is segmented into separate metallic sections that are electrically isolated from each other by non-conductive intermediaries. This segmentation prevents the formation of continuous electrical paths and potential differences that would lead to discharges, while still allowing the rails to be made of electrically conductive materials for mechanical strength.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Different parts of the rail system have different electrical properties: the rails themselves are electrically conductive for mechanical strength, while the intermediate elements and closing elements are electrically insulating to prevent discharges. This local differentiation of electrical properties allows the system to benefit from both conductive and insulating characteristics.

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

Effectively prevents electrical discharges and sparks between the rail extension device and the microwave oven door, enhancing user safety, appliance reliability, and maintaining the optical and mechanical integrity of the appliance.

Implementation Method 1

The at least one rail has an electrically insulating closing element at a front end viewed in the direction of its longitudinal axis, which faces a door of the microwave cooking appliance

Methodology Applied
Scientific EffectElectrical insulation: Electrical Resistance

Implementation Method 2

Electromagnetic radiation in the form of microwaves induces an electrical charge in electrically conductive components, resulting in a potential difference between several electrically conductive components that are insulated from one another

Methodology Applied
Scientific EffectElectromagnetic induction: Electromagnetic Induction

Data Source

PatentEP3967935A1Rail pull-out device for a microwave cooking device with an electrically insulating closing element on a rail front side and microwave cooking device
Publication Date: 2022.03.16 BSH HAUSGERATE GMBH
  • EP3967935A1 patent drawingFigure 1~2
  • EP3967935A1 patent drawingFigure 3~5
  • EP3967935A1 patent drawingFigure 6

AI summary

One aspect of the invention relates to a rail extension device (17) for a microwave oven (1), comprising a first elongated rail (18) and a second elongated rail (19) connected thereto, wherein the two rails (18, 19) are displaceable relative to each other in the direction of their longitudinal axes (A), wherein the two rails (18, 19) are at least partially made of an electrically conductive material, characterized in that at least one rail (19) has an electrically insulating end element (21) at a front end (20), which, when the rail extension device (17) is installed as intended in a cooking chamber (2) of the microwave oven (1), faces a door (1a) of the microwave oven (1). The invention also relates to a microwave oven (1).