Electromagnetic Induction Device Air Gap Elimination
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Solution Overview
Problem
Electromagnetic induction devices face issues such as air gaps in magnetic circuits leading to mechanical vibrations and noise, energy losses due to eddy currents, and high temperatures due to Joule losses, which affect their efficiency and usability, particularly in the aeronautical field where mass and noise reduction are critical.
Innovation Solution
A closed magnetic circuit without air gaps, using a sleeve with a circular internal section for winding the coil, laminated with multiple layers of magnetic material separated by insulators, and a local heat exchanger with flat surfaces for efficient heat transfer, along with a sleeve design featuring curved and flat parts to facilitate winding and cooling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If aluminum foil is used instead of copper to reduce mass, then weight is reduced, but ductility is much lower making coil winding difficult
Solution Approach 1:
The electrical conductor is segmented into multiple thin aluminum foils (typically 3-5 foils of 0.05-0.1mm thickness) rather than using a single thick conductor. This segmentation maintains flexibility and ease of winding while achieving weight reduction, as the thin foils can be bent and shaped more easily than thicker aluminum conductors would allow.
Solution Approach 2:
The patent uses composite construction by stacking multiple aluminum foils with insulating layers between them, creating a flexible composite conductor. This composite structure combines the weight advantage of aluminum with the flexibility needed for winding, as the thin layered construction behaves more like traditional copper conductors in terms of bendability.
2Ease of manufacture
If two-part magnetic circuit is used to assemble coils, then manufacturing is easier, but air gap forms causing mechanical vibrations and noise
Solution Approach 1:
A bonding agent or adhesive is introduced as an intermediary substance between the two magnetic circuit parts to eliminate the air gap. This bonding layer creates a rigid mechanical connection that prevents relative movement and vibration, while still allowing the two-part assembly structure to be used for manufacturing convenience.
Solution Approach 2:
The patent merges the two magnetic circuit parts into a single rigid structure through bonding, effectively treating them as one unified component. This merging eliminates the air gap and prevents relative movement between parts, thereby eliminating the source of mechanical vibrations and noise while maintaining the manufacturing advantage of separate part fabrication.
3Manufacturing precision
If magnetic circuit parts are ground to improve surface finish, then air gap is reduced, but manufacturing complexity increases
Solution Approach 1:
Instead of investing in complex precision grinding equipment and processes, the patent uses a simpler, more economical bonding approach that tolerates ordinary surface finishes. The bonding agent compensates for surface imperfections, making precision grinding unnecessary and thereby reducing manufacturing complexity while achieving the same air gap elimination effect.
4Loss of energy
If eddy currents are prevented by laminated magnetic circuit, then energy loss is reduced, but manufacturing complexity increases
Solution Approach 1:
The magnetic circuit is segmented into multiple thin laminations (typically 0.1-0.5mm thick sheets) stacked together with insulating coatings. This segmentation interrupts the path of eddy currents, forcing them to follow smaller circular paths within each lamination, thereby reducing eddy current losses. The same segmentation approach is used in the aluminum conductor foils.
Solution Approach 2:
The patent changes the physical parameter of lamination thickness to control eddy current losses. By selecting appropriate lamination thickness (0.1-0.5mm), the design optimizes the balance between reducing eddy current losses and maintaining manufacturing feasibility, as thinner laminations reduce losses but increase manufacturing complexity.
5Temperature
If Joule losses are high causing temperatures above 100°C, then device usability is limited, but cooling adds complexity
Solution Approach 1:
The patent employs liquid cooling through channels or heat sinks in contact with the magnetic circuit and/or coil assembly. This hydraulic cooling system efficiently removes Joule heat, maintaining operating temperatures at acceptable levels without requiring complex active cooling mechanisms, as passive liquid cooling can be integrated into the existing structure.
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 design reduces mechanical vibrations and noise, minimizes energy losses, and effectively manages heat, enhancing the efficiency and reliability of electromagnetic induction devices, particularly in reducing noise pollution and extending their operational lifespan.
Implementation Method 1
electromagnetic induction device comprising a closed magnetic circuit
Implementation Method 2
Another known technical problem of induction devices is the appearance of eddy currents in the magnetic circuit
Implementation Method 3
at least one said sleeve comprises an inner face whose cross-sectional shape is circular and matches the shape of said magnetic circuit, and an outer face comprising curved parts and flat parts, the induction device comprising a local heat exchanger in contact with the edit magnetic circuit
Data Source
Figure 1~3
Figure 4A~5
Figure 6A~7B
AI summary
Electromagnetic induction device (1) comprising a closed magnetic circuit (2), without an air gap, at least one first part (11) of which is substantially rectilinear and surrounded by a sleeve (3), said sleeve (3) being surrounded by an electrical conductor (4) which comprises at least one electrically insulated metal sheet on at least one of the faces thereof, characterised in that at least said or each said first part (11) of said magnetic circuit (2) has a circular cross-section.