Coreless Coil Terminal Positioning for Stable Inductance

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Solution Overview

Problem

Existing coil devices face issues with positional deviations of the coil with respect to the terminal, leading to uneven inductance characteristics and reliability concerns, particularly when using flat wire coils or coreless coils.

Innovation Solution

A coil device with a coreless coil and a terminal featuring a projection that regulates the coil's position, preventing positional deviations and ensuring smooth insertion into a core, along with a configuration that avoids friction and insulating film damage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If the coil is combined with the core together with the terminal during manufacturing, then the coil device can be assembled efficiently, but positional deviation of the coil with respect to the terminal occurs leading to uneven inductance characteristics

Engineering Contradiction:

Improveassembly efficiencyVSAvoidcoil position relative to terminal

Core Design Contradiction:

ProductivityVSManufacturing precision

Solution Approach 1:

The projection is formed on the terminal in advance during terminal manufacturing, creating a built-in positioning feature that will regulate coil position during assembly. This preliminary action ensures that when the coil is later combined with the terminal, its position is automatically regulated without requiring additional positioning operations or complex fixtures.

Inventive Principle:

Principle #10Preliminary action

2Ease of operation

If the columnar portion of the core contacts the inner peripheral surface of the coil during assembly, then the coil can be positioned, but inductance characteristics become uneven and reliability declines

Engineering Contradiction:

Improvecoil insertion into coreVSAvoidinductance characteristic consistency

Core Design Contradiction:

Ease of operationVSReliability

Solution Approach 1:

The projection acts as an intermediary positioning element between the terminal and the coil. Instead of allowing direct contact between the columnar portion and the coil's inner peripheral surface (which causes inductance variations), the projection regulates the coil's position relative to the terminal, ensuring proper alignment without harmful contact.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Device complexity

If flat wire is wound flatwise to form the coil, then the coil structure is simplified, but the end portion must be twisted for terminal connection causing inductance unevenness

Engineering Contradiction:

Improvecoil structureVSAvoidinductance characteristic consistency

Core Design Contradiction:

Device complexityVSManufacturing precision

Solution Approach 1:

The positioning function is extracted from the coil structure itself and transferred to the terminal through the projection. This allows the coil to maintain its simple flat-wound structure without requiring twisting or complex end treatments, while the projection on the terminal provides the necessary positioning to prevent inductance variations during assembly.

Inventive Principle:

Principle #2Taking out (Extraction)

Data Source

PatentUS12406797B2Coil device

Publication Date: 2025.09.02 TDK CORP

AI summary

An inductor includes a coreless coil and terminals connected to end portions of the coreless coil. Positioning portions regulating the position of the coreless coil are formed at the terminals.