Thermal Trip Device Linking Element Bimetal Deflection

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Solution Overview

Problem

Thermal magnetic circuit breakers face challenges in effectively interrupting current flow at lower thermal adjustments, leading to insufficient deflection and force of the bimetal element, which can result in inadequate protection against overload and potential damage to electrical circuits.

Innovation Solution

A thermal trip device with a bimetal element connected to a current conductive element and a linking element, where the bimetal element is heated indirectly by heat emitted from the conductive element, causing deflection and applying force to a tripping slide to interrupt the current flow, combined with a flexible and conductive linking element to manage temperature and redirect electrical current, allowing for adjustable thermal adjustment without exceeding permissible temperatures.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If lower thermal adjustment is used (70% ln), then the breaker trips at lower current, but the bimetal element temperature is insufficient to generate adequate deflection and force

Engineering Contradiction:

Improveoverload protection reliabilityVSAvoidbimetal element deflection force

Core Design Contradiction:

ReliabilityVSForce

Solution Approach 1:

The patent introduces a linking element as an intermediary between the current conductive element and the bimetal element. This linking element redirects electrical current to flow through the bimetal element, generating additional Joule heating that compensates for the lower temperature at reduced thermal adjustments, thereby maintaining sufficient deflection force for reliable tripping.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent modifies the electrical current path parameter by introducing the linking element that redirects current flow. This changes the thermal parameters of the bimetal element by adding Joule heating, allowing the system to maintain adequate deflection force even at lower thermal adjustments where conventional designs would fail.

Inventive Principle:

Principle #35Parameter changes

2Force

If higher electrical current flows through the conductive element, then higher temperature is generated for better bimetal element performance, but the temperature may exceed permissible limits

Engineering Contradiction:

Improvebimetal element deflection forceVSAvoidconductive element temperature

Core Design Contradiction:

ForceVSTemperature

Solution Approach 1:

The patent segments the current path by introducing a separate linking element that provides an alternative route for electrical current. This segmentation allows the main conductive element to operate within safe temperature limits while the bimetal element receives sufficient thermal energy through the linking element's current path, maintaining force without excessive temperature.

Inventive Principle:

Principle #1Segmentation

3Device complexity

If the bimetal element is directly heated by the conductive element, then simpler structure is achieved, but insufficient temperature control and force generation at lower adjustments

Engineering Contradiction:

Improvethermal trip device structureVSAvoidtripping reliability at lower adjustments

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The linking element serves as an intermediary that provides controlled thermal coupling between the current conductive element and the bimetal element. This intermediary structure enables precise temperature control and sufficient force generation at lower thermal adjustments while maintaining a relatively simple overall device structure.

Inventive Principle:

Principle #24Intermediary (Mediator)

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 enables efficient interruption of current flow during overloads, effectively protecting electrical circuits from damage by optimizing the movement and force of the bimetal element, ensuring reliable operation within temperature constraints.

Implementation Method 1

the bimetal element is heated indirectly by heat emitted from the conductive element

Methodology Applied

Scientific EffectThermal radiation: Thermal Radiation

Implementation Method 2

the bimetal element is able to be connected with a linking element extending between the bimetal element and the current conductive element in order to redirect the electrical current at least partially

Methodology Applied

Scientific EffectJoule heating: Joule Heating

Data Source

PatentEP2897152B1Thermal trip device, switching device, thermal magnetic circuit breaker and method for protecting an electric circuit

Publication Date: 2017.03.29 SIEMENS AG

AI summary

The present invention relates to a thermal trip device of a thermal magnet circuit breaker for protecting an electrical circuit from damage by overload, a switching device and a thermal magnetic circuit breaker having at least the thermal trip device mentioned above, wherein the thermal trip device has at least a bimetal element in order to be arranged with its first end at a current conductive element for conducting electrical current and in order to be arranged with its second end at a tripping slide adapted to interrupting a current flow, wherein the bimetal element is able to be connected with a linking element extending between the bimetal element and the current conductive element in order to redirect the electrical current at least partially. Furthermore, the present invention relates to a method for protecting an electric circuit from damage by overload by means of the thermal trip device of a thermal magnet circuit breaker.