Inductor Core Magnetic Powder Density Distribution
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing inductor elements face challenges with uneven density and susceptibility to cracks due to low pressure transmission during molding, leading to compromised DC superposition characteristics and withstand voltage.
Innovation Solution
An inductor element design with a core containing magnetic powder and resin, where the density of magnetic powder varies strategically around the winding axis, ensuring higher density near the axis center and maintaining sufficient density in neighboring regions, preventing cracks and improving inductance and DC superposition characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If re-pressing is performed to increase density for improving DC superposition characteristics, then density increases, but pressure transmission becomes insufficient and density becomes uneven
Solution Approach 1:
The patent applies local quality by defining specific neighboring regions around the wire-winding portion (inner circumferential, end surface regions) and setting different minimum magnetic powder area ratios for these regions compared to the central region. This ensures localized density control where it is most critical for preventing cracks and maintaining electrical characteristics, rather than requiring uniform density throughout the entire core.
Solution Approach 2:
The patent changes the parameter of magnetic powder distribution by specifying minimum area ratios (Sβ1≥50%, Sβ2≥50%, Sβ3≥50%) in neighboring regions and their relationship to the central region (Sα-Sβ1≥-5.0%, Sα-Sβ4≥-5.0%). This parameter-based approach allows quantitative control of density distribution to prevent cracks while maintaining manufacturability.
2Quantity of substance
If high pressure is applied during re-pressing to increase density, then density increases, but coil film breaks and withstand voltage decreases
Solution Approach 1:
The patent changes the approach from controlling absolute pressure to controlling magnetic powder distribution parameters (area ratios Sα, Sβ1, Sβ2, Sβ3 and their differences). This allows achieving the necessary density for crack prevention through optimized powder distribution rather than excessive pressure, thereby protecting the coil film and maintaining withstand voltage.
3Reliability
If density is increased to improve DC superposition characteristics, then DC superposition characteristics improve, but cracks occur during use
Solution Approach 1:
The patent identifies that cracks occur in specific neighboring regions around the wire-winding portion where magnetic powder density is insufficient. By applying local quality control with minimum area ratio requirements (Sβ1≥50%, Sβ2≥50%, Sβ3≥50%) in these critical regions, the patent prevents cracks while maintaining the overall density needed for DC superposition characteristics.
Solution Approach 2:
The patent applies preliminary anti-action by pre-establishing the magnetic powder distribution parameters before the inductor goes into service. By ensuring minimum area ratios in neighboring regions during manufacturing, the patent prevents crack formation in advance, rather than addressing cracks after they occur during use.
Data Source
AI summary
An inductor element includes a wire-winding portion and a core portion. In the wire-winding portion, a conductor is wound in a coil shape. The core portion surrounds the wire-winding portion and contains a magnetic powder and a resin. The wire-winding portion includes an inner circumferential surface. A winding-wire inner circumferential neighboring region is a region of the core portion within a distance from the inner circumferential surface toward a winding axis of the wire-winding portion. An inner-core central region is a region of the core portion within a distance from the winding axis center toward an existing region of the wire-winding portion in an outward direction perpendicular to the winding axis center. Sα−Sβ1≥5.0% is satisfied, where Sα(%) and Sβ1(%) are respectively an area ratio of a magnetic powder in the inner-core central region and the winding-wire inner circumferential neighboring region.