Temperature-Dependent Switch Sealing via Curved Peripheral Edge

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Solution Overview

Problem

Existing temperature-dependent switches face issues with sealing and contamination ingress due to the waviness of insulating films and inadequate pressure stability, leading to paint and lacquer penetration into the switch interior.

Innovation Solution

The upper section of the peripheral wall is designed as a continuously curved edge that presses on the protective film, creating a sealing contact and preventing contamination entry, allowing for improved sealing and assembly as a Surface Mounted Device (SMD) without additional contact lugs or pigtails.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the insulating film is folded over on the upper side of the cover part, then the sealing is improved, but the insulating film becomes wavy and forms rosettes that cannot be securely sealed

Engineering Contradiction:
Improvesealing efficacyVSAvoidinsulating film flatness
Core Design Contradiction:
ReliabilityVSShape

Solution Approach 1:

The upper section of the peripheral wall is designed with a curved configuration that overlaps the cover part, creating a continuous sealing surface. This curved design eliminates the waviness and rosette formation that occur with flat folded edges, providing a secure seal against paint and lacquer penetration while maintaining structural integrity.

Inventive Principle:
Principle #14Spheroidality (Curvature)

Solution Approach 2:

The insulating film is nested between the upper section of the peripheral wall and the cover part, with the curved wall section pressing the film against the cover part's upper side. This nested arrangement ensures the film remains flat and securely sealed, preventing contamination ingress while maintaining electrical insulation.

Inventive Principle:
Principle #7Nested doll (Nesting)

2Reliability

If additional sealing measures are added to prevent contamination ingress, then the sealing is improved, but the device complexity increases

Engineering Contradiction:
Improvecontamination protectionVSAvoidsealing structure complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The upper section of the peripheral wall serves multiple functions: it provides structural support, creates the sealing surface by overlapping the cover part, and presses the insulating film against the cover part. This multi-functional design achieves effective contamination protection without adding separate sealing components, thereby avoiding increased device complexity.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Solution Approach 2:

The sealing function is merged into the peripheral wall structure itself rather than being a separate component. The curved upper section of the wall combines the sealing, support, and insulation retention functions into a single integrated structure, simplifying the overall device while maintaining effective contamination protection.

Inventive Principle:
Principle #5Merging (Combining)

3Force

If the upper section of the peripheral wall is bent radially inwards, then the cover part is pressed firmly, but the insulating film becomes wavy and sealing is compromised

Engineering Contradiction:
Improvepressing force on cover partVSAvoidsealing integrity
Core Design Contradiction:
ForceVSReliability

Solution Approach 1:

Instead of bending the upper section radially inwards in a flat manner, it is designed with a curved configuration that naturally distributes the pressing force while maintaining contact with the insulating film. This curved geometry prevents film waviness and rosette formation, ensuring sealing integrity is maintained even under firm pressing conditions.

Inventive Principle:
Principle #14Spheroidality (Curvature)

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 enhances sealing efficacy, prevents contamination ingress, and enables SMD assembly with reduced complexity, ensuring reliable operation and reduced manufacturing defects.

Implementation Method 1

The upper section of the peripheral wall of the lower part that overlaps the cover part is designed as a continuously curved edge that presses on the protective film with its front side

Methodology Applied
Scientific EffectSealing contact:

Implementation Method 2

a bimetallic disc slipped over the moving contact part... the bimetallic disc changes its configuration and works against the spring snap-in disc in such a way that it separates the movable contact part from the stationary counter-contact

Methodology Applied
Scientific EffectBimetallic effect: Bi-Metallic Strip

Implementation Method 3

The spring snap-action disc presses the movable contact part against a stationary mating contact inside the cover part

Methodology Applied
Scientific EffectSpring force: Spring

Data Source

PatentEP3270401B8Temperature-dependent switch with insulating disc
Publication Date: 2019.06.26 THERMIK GERAETEBAU GMBH

AI summary

A temperature-dependent switch (10) is provided with a housing comprising a cover part (15) with a top surface (21) and a bottom part (14) with a circumferential wall (19) whose upper section (20) overlaps the cover part (15). The housing includes at least one first outer contact surface (38) arranged on the top surface of the cover part (15), at least one second outer contact surface (39) arranged on the outside of the housing, and at least one protective film (13, 22) arranged at least on the top surface of the cover part (15), wherein the upper section (20) of the circumferential wall (19) of the bottom part (14), which overlaps the cover part (15), holds the cover part (15) against the bottom part (14) with the protective film (13) interposed. The housing contains a temperature-dependent switching mechanism which, depending on its temperature, establishes or opens an electrically conductive connection between the first and the second outer contact surface (38, 39).The upper section (20) of the circumferential wall (19) of the lower part (14), which overlaps the lid part (15), is formed as a continuously curved edge (41) which presses with its front face (42) onto the protective film (13) (Fig. 2).