Bimetal Part with Opposing Stamped Regions for Switch Stability

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Solution Overview

Problem

Existing temperature-dependent switches with bimetal parts face issues such as unpredictable creeping phases, mechanical stresses, and instability in transition temperatures due to asymmetrical loads, leading to contact chatter and erosion, especially in designs where the bimetal part carries current.

Innovation Solution

A bimetal part with an inner and outer region, stamped in opposite directions to create opposing forces and prevent creeping phases, ensuring stable switching points and uniform mechanical loads, allowing for reliable and reproducible switching without the need for spring snap-action discs.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the bimetal part is formed as a spring and carries current, then the switch responds to both temperature and current, but the creeping phase causes contact pressure reduction leading to contact erosion and chatter

Engineering Contradiction:

Improveswitching reliabilityVSAvoidcontact erosion and chatter

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The bimetal part is segmented into an inner region and an outer region that are mechanically separated in certain portions by stamped gaps. This segmentation allows the inner and outer regions to deform independently in opposite directions, suppressing the creeping phase while maintaining contact pressure stability.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The inner and outer regions are stamped in opposite directions to create asymmetrical deformation patterns. The inner region is stamped in one direction while the outer region is stamped in the opposite direction, generating opposing forces that stabilize the switching point and eliminate creeping phase.

Inventive Principle:

Principle #4Asymmetry

2Manufacturing precision

If the bimetal part is designed as a spring with asymmetrical structure, then switching is achieved, but mechanical stresses cause instability in transition temperatures

Engineering Contradiction:

Improvetransition temperature stabilityVSAvoidmechanical stress stability

Core Design Contradiction:

Manufacturing precisionVSStability of the object's composition

Solution Approach 1:

The bimetal part employs asymmetrical stamping where the inner region and outer region are stamped in opposite directions. This controlled asymmetry creates opposing mechanical forces that compensate for each other, stabilizing the transition temperature against mechanical stress variations.

Inventive Principle:

Principle #4Asymmetry

Solution Approach 2:

The inner and outer regions act as counterbalancing elements, with the inner region stamped in one direction and the outer region stamped in the opposite direction. These opposing deformations create counteracting forces that neutralize mechanical stresses and stabilize the switching characteristics.

Inventive Principle:

Principle #8Anti-weight (Counterweight)

3Device complexity

If the bimetal part is formed as a disc loosely inserted, then current flow through the bimetal is avoided, but a spring snap-action disc is required adding complexity

Engineering Contradiction:

Improveswitch structure complexityVSAvoidswitching performance

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The invention merges the functions of the bimetal part and the spring snap-action disc into a single integrated structure. The bimetal part itself provides both the temperature-sensitive switching function and the spring snap-action mechanism, eliminating the need for a separate disc and simplifying the overall device.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The bimetal part is designed to perform multiple functions simultaneously: it acts as the temperature-sensitive element, the spring mechanism, and the snap-action switching component. This multi-functionality reduces the number of parts required while maintaining reliable switching performance.

Inventive Principle:

Principle #6Universality (Multi-functionality)

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 provides stable, long-term reliable switching with minimal hysteresis and improved ageing resistance, enabling switches to maintain consistent performance across multiple cycles without mechanical or thermal degradation.

Implementation Method 1

a multi-layered active structural part in sheet form comprising two, three or four components with different coefficients of expansion connected inseparably to one another

Methodology Applied

Scientific EffectDifferential thermal expansion: Thermal Expansion

Implementation Method 2

current flows through the bimetal part itself, so that it heats up as a result of the current flowing through the switch

Methodology Applied

Scientific EffectJoule heating: Joule Heating

Data Source

PatentUS9355801B2Bimetal part and temperature-dependent switch equipped therewith

Publication Date: 2016.05.31 HOFSAESS MARCEL P

AI summary

A bimetal part (10) for use as an active switching element in a temperature-dependent switch has at least one inner region (13) and an outer region (12) surrounding the at least one inner region (13), the inner region (13) and the outer region (12) being formed such that in certain portions they are in one piece with one another and in certain portions they are mechanically separated from one another and being stamped in opposite directions, and at least one contact area (21) being provided on the inner region (13).