Metal Magnetic Coil Core Gap Layout for Stable Inductance
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Solution Overview
Problem
Conventional inductors with ferrite cores experience significant changes in inductance due to temperature variations, while those with metal magnetic cores have lower inductance and are sensitive to temperature changes.
Innovation Solution
A coil device design featuring a main core with a middle leg and an outer leg, where the gap between the middle leg and a sub core is wider than the gap between the outer leg and the sub core, utilizing metal magnetic materials with a relative permeability of 15-100, and fixed with an adhesive agent only on the top surface of the middle leg to maintain stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a core made of ferrite material is used to improve inductance, then inductance increases, but characteristics change easily by temperature change
Solution Approach 1:
The patent changes the material parameter from ferrite to metal magnetic material, which has different temperature characteristics. This parameter change allows the core to maintain stable inductance characteristics across temperature variations while still achieving high inductance through the optimized gap structure
Solution Approach 2:
The patent applies different gap widths at different locations: a first gap between the middle leg and sub core, and a second gap between the outer leg and sub core. This local differentiation of gap quality optimizes the magnetic flux distribution, allowing high inductance to be achieved with metal magnetic material while maintaining temperature stability
2Stability of the object's composition
If a core including a metal magnetic material is used to reduce temperature sensitivity, then temperature stability improves, but inductance becomes small
Solution Approach 1:
The patent optimizes the gap parameter between the middle leg and sub core to a specific range (15-55 μm). This parameter adjustment compensates for the lower permeability of metal magnetic material, enabling high inductance to be achieved while maintaining temperature stability
Solution Approach 2:
The patent creates a localized magnetic path optimization by setting the first gap (middle leg to sub core) differently from the second gap (outer leg to sub core). This local quality differentiation concentrates the magnetic flux where needed, achieving high inductance with metal magnetic material
3Volume of moving object
If the gap between the middle leg and sub core is made larger to improve inductance, then inductance increases, but the gap between outer leg and sub core may broaden
Solution Approach 1:
The patent differentiates the gap design between the middle leg and outer leg positions. The first gap (middle leg to sub core) is set to 15-55 μm for inductance optimization, while the second gap (outer leg to sub core) is minimized through adhesive application. This local quality differentiation allows inductance improvement without compromising overall assembly precision
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 achieves high inductance with minimal temperature-dependent characteristic changes, even at high temperatures, and allows for low DC resistance and large current capacity, enhancing durability and stability.
Implementation Method 1
the sub core is fixed to the main core with an adhesive agent disposed on a top surface of the middle leg
Implementation Method 2
a coil device according to the present invention comprises: a main core including a middle leg for winding a coil body... capable of obtaining a high inductance
Data Source
AI summary
A coil device includes a main core and a sub core. The main core includes a middle leg for winding a coil body and an outer leg connected with the middle leg via a base portion. The sub core is disposed to face the base portion across the middle leg. A gap between the middle leg and the sub core is wider than that between the outer leg and the sub core.