Magnetic Core Through Portion Design for Induction Heating
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Solution Overview
Problem
Existing image heating apparatuses using electromagnetic induction heating face issues with uneven heating due to through portions in magnetic cores, leading to reduced heat generation efficiency and frequent contact between electrical wires and image heating members, resulting in wear and limited design flexibility.
Innovation Solution
An image heating apparatus with a magnetic core having a through portion where the opening on the interior side overlaps the core, reducing flux irregularities and allowing the electrical wire to be laid outside the image heating member, thus minimizing contact and enhancing heat generation efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a through portion is formed in the magnetic core to allow electrical wires to pass through, then the wires can be laid inside the image heating member, but this causes uneven heating and flux irregularities
Solution Approach 1:
The electrical wires are extracted from the interior of the magnetic core and relocated to the exterior surface. The through portion is formed only to the extent necessary to allow wire passage, and the magnetic core material is restored around the wire passage area to eliminate flux irregularities while maintaining wire accessibility.
Solution Approach 2:
The magnetic core is designed with differentiated local properties: a through portion is created only in the specific region where wire passage is needed, while the rest of the core maintains its continuous magnetic path. The wire passage area is locally modified to accommodate wires without compromising the overall magnetic flux distribution.
2Measurement precision
If the electrical wire is laid between the image heating member and magnetic core, then temperature detection is enabled, but the wire and image heating member frequently contact causing wear
Solution Approach 1:
The electrical wire is extracted from the interior space between the image heating member and magnetic core, and rerouted to pass through the magnetic core's through portion to emerge on the exterior. This eliminates the frequent contact between the wire and the rotating image heating member, preventing wear while maintaining temperature detection capability.
3Loss of energy
If the through portion opening on the interior side does not overlap the magnetic core, then flux leakage is reduced, but the electrical wire cannot be properly routed
Solution Approach 1:
The through portion is designed with asymmetric geometry where the opening on the interior side (facing the image heating member) is positioned to overlap the magnetic core area, while the opening on the exterior side is positioned differently. This localized configuration allows wire passage through the overlapping region without causing significant flux leakage, as the magnetic flux paths are concentrated in different areas.
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 reduces uneven heating, prolongs the life of components, and increases design flexibility by minimizing contact between electrical wires and the image heating member, while maintaining efficient heat generation.
Implementation Method 1
The excitation coil generates a magnetic field and thereby causes magnetic fluxes in the conductive layer lying in the magnetic field. This produces eddy currents within the conductive layer to generate heat.
Implementation Method 2
a magnetic core arranged inside the image heating member... For improved heat generation efficiency, the distance between the image heating member and the magnetic core needs to be reduced.
Data Source
AI summary
A temperature detection unit is arranged in a position between a magnetic field generation coil and a magnetic core that lies inside a heat generation member. A cut portion for exposing the temperature detection unit through the magnetic core has a thickness when seen in a cross section in the direction of a magnetic flux.