Electromagnet Load Capacity via Current Rise Time

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Solution Overview

Problem

Existing magnetic lifting devices face challenges in maintaining a safe attachment to loads with varying magnetic properties and debris interference, as the traditional safety margin is insufficient in ensuring a secure lift.

Innovation Solution

An apparatus comprising a direct current power source, an electromagnet with a coil, a current measurement device, and a user interface, where the controller measures the current rise time to determine the load capacity based on the nominal current value, allowing for real-time adjustment and display of the load capacity and usage level, ensuring safe attachment even with different types of loads and debris.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a fixed safety margin is applied to the load capacity, then the lifting device can handle standard loads, but it becomes insufficient when magnetic forces vary considerably due to different load types or debris

Engineering Contradiction:
Improveattachment safetyVSAvoidadaptability to varying load conditions
Core Design Contradiction:
ReliabilityVSAdaptability or versatility

Solution Approach 1:

The load capacity is no longer fixed but dynamically adjusted based on real-time measurement of the rise time constant. The system continuously monitors the electrical characteristics of the coil to determine the actual magnetic attachment strength, allowing the load capacity to adapt automatically to different load types and contact conditions, thereby resolving the contradiction between reliability and adaptability

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The system implements a feedback mechanism where the measured rise time constant is used to update the load capacity determination. By continuously monitoring the electrical response of the coil and comparing it against reference values, the system provides real-time feedback on the actual magnetic attachment strength, enabling automatic adjustment of the safe load capacity to maintain reliability across varying conditions

Inventive Principle:
Principle #23Feedback

2Reliability

If the load capacity is determined by a conservative fixed value, then safety is maintained for unknown loads, but the lifting device cannot optimize performance for specific load types

Engineering Contradiction:
Improvesafety marginVSAvoidlifting efficiency
Core Design Contradiction:
ReliabilityVSProductivity

Solution Approach 1:

The lifting device performs self-diagnosis by automatically measuring the rise time constant and determining its own safe load capacity based on the actual magnetic attachment conditions. This self-service capability eliminates the need for conservative fixed values or manual assessment, allowing the system to optimize lifting efficiency for each specific load while maintaining safety through automated real-time evaluation

Inventive Principle:
Principle #25Self-service

3Ease of operation

If debris is present between the load and lifting device, then contact is improved for some loads, but magnetic attachment strength is reduced leading to unsafe lifting

Engineering Contradiction:
Improvecontact establishmentVSAvoidmagnetic attachment strength
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

The system detects the presence and impact of debris by monitoring changes in the rise time constant. When debris is present, it alters the electrical characteristics of the coil, which is detected by the control unit. The system then provides feedback to adjust the load capacity determination or alert the operator, maintaining reliability despite the ease of contact establishment provided by debris

Inventive Principle:
Principle #23Feedback

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 provides a dynamic and safe load capacity determination, adapting to varying load conditions, ensuring reliable and secure lifting by accurately assessing the magnetic attachment strength based on the rise time of the current, thus enhancing safety in magnetic lifting operations.

Implementation Method 1

an electromagnet (106) comprising a coil (108) connectable to the direct current power source (104) for feeding current to the coil (108) for attaching to the load by a magnetic force

Methodology Applied
Scientific EffectElectromagnetism: Electromagnet

Implementation Method 2

a current measurement device (112) connected to the coil (108)

Methodology Applied
Scientific EffectElectrical current measurement: Ohmmeter

Data Source

PatentEP3674249B1Apparatus for magnetically attaching to a load
Publication Date: 2023.08.16 TARKMET OY
  • EP3674249B1 patent drawingFigure 1
  • EP3674249B1 patent drawingFigure 2a
  • EP3674249B1 patent drawingFigure 2b

AI summary

Apparatus for magnetically attaching to a load comprising: a direct current power source (104); an electromagnet comprising a coil (108) connectable to the direct current power source for feeding current to the coil for attaching to a load by a magnetic force; a current measurement device connected to the coil; a user interface (110) for displaying information indicating a load capacity of the apparatus; and a controller operatively connected to the direct current power source, the coil, the current measurement device (112) and the user interface to cause: connecting the direct current power source to the coil; measuring current of the coil; determining a rise time of the current to a nominal value of current of the coil, when the load is attached to the apparatus; determining a load capacity and/or usage level of the load capacity of the apparatus based on the rise time of the current to the nominal value; and displaying the load capacity on the user interface.