Electromagnetic Trip Unit with Adjustable Air Gap

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Solution Overview

Problem

Existing solenoid type electromagnetic trip units face high costs due to the need for increasing the number of coil turns to meet low current threshold requirements, which is inefficient and costly.

Innovation Solution

A two-stage adjustable magnetic field air gap is achieved by modifying the movable core, allowing for different current thresholds without changing other components, using a magnetic field air gap adjusting assembly that includes a trip lever, rocker arm, and magnetic adjusting screw to adjust the air gaps.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If the number of coil turns is increased to achieve low current threshold, then the current threshold is reduced, but the product cost increases

Engineering Contradiction:

Improvecurrent thresholdVSAvoidproduct cost

Core Design Contradiction:

Measurement precisionVSEase of manufacture

Solution Approach 1:

The patent changes the magnetic field air gap parameter to adjust the current threshold. By modifying the air gap distance between the movable core and static core, the magnetic field strength is changed, which directly affects the trip current threshold. This approach allows cost-effective adjustment without increasing coil turns

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent segments the air gap adjustment into two distinct stages: a first adjustable air gap (d1) and a second fixed air gap (d2). The movable core body is divided into different sections with a step structure, creating two separate magnetic field regions. This segmentation enables precise control of the trip threshold through the first air gap while maintaining a stable second air gap for reliability

Inventive Principle:

Principle #1Segmentation

2Adaptability or versatility

If the magnetic field air gap is adjusted to change current thresholds, then different current thresholds can be selected, but the device complexity increases

Engineering Contradiction:

Improvecurrent threshold selectionVSAvoidstructure complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent introduces a dynamic adjustment mechanism where the movable core can be positioned at different locations along its travel path. The magnetic field air gap adjusting assembly allows the movable core to be set at different positions, creating variable first air gap distances. This dynamic adjustability provides multiple current threshold options while using a relatively simple mechanical structure

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent uses a magnetic field air gap adjusting assembly as an intermediary mechanism between the user's adjustment action and the magnetic field configuration. This assembly includes components like adjustment screws, springs, and positioning mechanisms that translate user input into precise air gap adjustments, simplifying the overall control while enabling versatile threshold selection

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

This solution allows for adjustable current thresholds, reducing product costs and improving efficiency by enabling precise adjustment of magnetic field air gaps, ensuring reliable operation across varying current conditions.

Implementation Method 1

the electromagnetic trip unit comprises a movable core, an upper static core and a lower static core... When the electromagnetic trip unit is not released, a first magnetic field air gap is formed between the movable core body end and the lower static core end

Methodology Applied

Scientific EffectElectromagnetic induction: Electromagnetic Induction

Implementation Method 2

A movable core body end of a movable core body of the movable core faces and approaches the lower static core end of the lower static core. When the electromagnetic trip unit is not released, a first magnetic field air gap is formed between the movable core body end and the lower static core end

Methodology Applied

Scientific EffectMagnetic field: Magnetic Field

Data Source

PatentUS11482392B2Electromagnetic trip unit

Publication Date: 2022.10.25 SCHNEIDER ELECTRIC IND SAS

AI summary

An electromagnetic trip unit, wherein: the electromagnetic trip unit includes a movable core, an upper static core and a lower static core; the movable core can move relative to the upper static core and the lower static core in the upper static core and the lower static core; a movable core body end of a movable core body of the movable core faces and approaches the lower static core end of the lower static core, when the electromagnetic trip unit is not released, a first magnetic field air gap is formed between the movable core body end and the lower static core end; the movable core body of the movable core is also provided with a movable core body step, when the electromagnetic trip unit is not released, a second magnetic field air gap is formed between the movable core body step and the lower static core end.