Ferromagnetic Core Stabilization in Induction Heating Fixing Devices
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Solution Overview
Problem
Existing electromagnetic induction heating systems for fixing devices in image forming apparatuses face inefficiencies due to side core breakage during molding, which disrupts the uniform direction of magnetic flux and reduces heat generation efficiency.
Innovation Solution
The use of a holder with spherical marks created by stabilizing members to securely insert and stabilize ferromagnetic cores, preventing breakage and maintaining high heat generation efficiency by ensuring proper alignment and contact of the ferromagnetic cores during the molding process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the side core is made with a center thicker than both ends to reduce warping, then the reliability of the side core is improved, but the volume of the side core is reduced by notches which decreases heat generation efficiency
Solution Approach 1:
The patent changes the geometric parameters of the side core by adding protrusions at both ends that extend beyond the central portion. This parameter modification allows the side core to maintain sufficient volume for heat generation while the protrusions provide structural reinforcement to reduce warping during insert-molding, thus resolving the contradiction between reliability and energy efficiency
Solution Approach 2:
The protrusions are designed in advance as integral parts of the side core structure before insert-molding. These pre-formed protrusions prevent warping during the molding process, eliminating the need for post-processing notches that would reduce volume, thereby maintaining heat generation efficiency while ensuring reliability
2Loss of energy
If the side core is insert-molded in the holder to position it closer to the fixing member, then the heat generation efficiency is improved, but the side core may be broken if it is warped during molding
Solution Approach 1:
The side core is pre-formed with protrusions at both ends that extend beyond the central portion. This preliminary structural design prevents warping during the insert-molding process, allowing the side core to be successfully molded in the holder position close to the fixing member without breaking, thus maintaining both efficiency and reliability
Solution Approach 2:
The protrusions act as structural reinforcements that cushion against the warping forces experienced during insert-molding. By providing this beforehand cushioning, the side core can withstand the molding process stresses without breaking, enabling close positioning to the fixing member for high efficiency
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 configuration enhances the heat generation efficiency by preventing side core breakage and maintaining uniform magnetic flux direction, thus improving the overall heating performance of the fixing device.
Implementation Method 1
a high-frequency alternating current supplied to the excitation coil forms an alternating magnetic field around the excitation coil, which generates eddy currents on and around the surface of the support roller
Implementation Method 2
When the eddy currents are generated around the support roller serving as a heat generator, the electrical resistance of the support roller leads to Joule heating of the support roller, thereby heating the fixing belt stretched over the support roller
Implementation Method 3
a ferromagnetic core to form a magnetic path to direct the magnetic flux generated by the excitation coil to the fixing member
Data Source
AI summary
A fixing device includes a fixing member, which includes heat-generating layer, and an induction heater to inductively heat the fixing member. The induction heater includes an excitation coil disposed facing an outer circumferential surface of the fixing member to generate a magnetic flux, a ferromagnetic core assembly containing a ferromagnetic core to form a magnetic path to direct the magnetic flux generated by the excitation coil to the fixing member, and a holder to hold the excitation coil and the ferromagnetic core assembly. The ferromagnetic core is insert-molded in and covered by the holder. The holder has a plurality of spherical marks created by a plurality of stabilizing members each having a spherical tip to stabilize the ferromagnetic core in a mold.