Temperature-Dependent Switch Shielding Pot for Arc Suppression

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Solution Overview

Problem

Existing temperature-dependent switches face issues with electromagnetic shielding, particularly due to changes in the electromagnetic environment, leading to problems like undesired arcing when switches are opened, which can affect their reliability and service life.

Innovation Solution

A shielding pot made of electrically conductive metallic material, such as steel, is placed on the switch from below, providing additional protection against electromagnetic fields without the need for a complete shielding housing, and is mechanically secured using crimping, clamping, or resin to ensure effective shielding and mechanical protection.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If a complete shielding housing is used to protect the switch from electromagnetic fields, then electromagnetic shielding is improved, but device complexity and production costs increase

Engineering Contradiction:
Improveelectromagnetic shieldingVSAvoidhousing structure
Core Design Contradiction:
Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The shielding function is segmented from the housing structure. Instead of using a complete shielding housing, only a shielding pot (base part) made of electrically conductive material is used to provide the necessary electromagnetic shielding at the critical area where the switching mechanism is located, while the rest of the housing can be made from non-conductive materials.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The shielding function is extracted as a separate component (shielding pot) that can be independently designed and manufactured. The shielding pot is placed into the housing from below, providing electromagnetic shielding without requiring the entire housing to be made of conductive material, thus reducing overall device complexity.

Inventive Principle:
Principle #2Taking out (Extraction)

2Object-affected harmful factors

If a complete shielding housing is used to protect the switch from electromagnetic fields, then electromagnetic shielding is improved, but production costs increase

Engineering Contradiction:
Improveelectromagnetic shieldingVSAvoidproduction cost
Core Design Contradiction:
Object-affected harmful factorsVSEase of manufacture

Solution Approach 1:

The manufacturing process is segmented into separate steps: first producing the housing (which can be made from inexpensive non-conductive materials), then separately producing the shielding pot from conductive material, and finally assembling them together. This allows each component to be optimized independently and manufactured using appropriate processes.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The shielding function is extracted as a separate component that can be manufactured independently and added to the housing. This avoids the need to manufacture an expensive complete shielding housing, reducing overall production costs while maintaining necessary electromagnetic shielding performance.

Inventive Principle:
Principle #2Taking out (Extraction)

3Device complexity

If the switch is placed in a changed electromagnetic environment without additional shielding, then device complexity is reduced, but reliability deteriorates due to undesired arcing

Engineering Contradiction:
Improveshielding structureVSAvoidswitch operation
Core Design Contradiction:
Device complexityVSReliability

Solution Approach 1:

The shielding pot acts as an intermediary component between the switching mechanism and the external electromagnetic environment. It provides a localized electromagnetic shield around the critical switching area, preventing harmful electromagnetic fields from causing undesired arcing while maintaining overall device simplicity.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The shielding pot is positioned at the base of the housing before the switch is fully assembled, creating a preliminary electromagnetic barrier that prevents harmful electromagnetic fields from reaching the switching mechanism. This preliminary protection prevents undesired arcing before it can occur during switch operation.

Inventive Principle:
Principle #9Preliminary anti-action

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 significantly improves electromagnetic shielding and mechanical protection for existing temperature-dependent switches, preventing arcing and extending their service life without increasing production costs or requiring new switch designs, allowing them to function reliably in changed electromagnetic environments.

Implementation Method 1

A shielding pot made of an electrically conductive, metallic material, in which the housing is used with its underside first

Methodology Applied
Scientific EffectElectromagnetic shielding: Faraday Cage

Implementation Method 2

a bimetallic disc slipped over the moving contact part. The spring washer carries a so-called movable contact part which presses the spring washer against a stationary contact part inside the cover part

Methodology Applied
Scientific EffectBimetallic effect: Bi-Metallic Strip

Implementation Method 3

The temperature-dependent switching mechanism here includes a spring snap-action disc, which carries the moving contact part

Methodology Applied
Scientific EffectSpring elasticity: Spring

Implementation Method 4

it is brought into thermal contact with the device to be protected, for example via one of its outer surfaces, so that the temperature of the device to be protected influences the temperature of the switching mechanism

Methodology Applied
Scientific EffectThermal conduction: Conduction (thermal)

Data Source

PatentEP2743954B1Temperature-dependent switch
Publication Date: 2019.08.21 HOFSAESS MARCEL P
  • EP2743954B1 patent drawingFigure 1
  • EP2743954B1 patent drawingFigure 2
  • EP2743954B1 patent drawingFigure 3~5

AI summary

The switch (1') has a housing comprising a cover part and a base part with a circulating wall and a lower side. A temperature-dependant switching unit is arranged in the housing such that an electrical conductive connection between two external connections (22) is established or opened depending on temperature. The external connections are provided at an upper side (25) of the housing. A screen pot (41) is made of an electrical conductive metallic material i.e. steel. The housing with the lower side is inserted into the screen pot. An independent claim is also included for a method for final assembly of a temperature-dependant switch.