Adjustable Toroidal Inductor With Thermal-Locked Gap Tuning

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Solution Overview

Problem

Conventional inductors, such as toroidal inductors, have fixed inductance values that cannot be easily adjusted, requiring cumbersome methods like adding or removing turns or repositioning windings, which are often impractical and result in scrap or re-winding, limiting their application in adjustable circuits.

Innovation Solution

An adjustable inductor design featuring a toroidal core with multiple gaps filled with compressible and rigid gap materials, a force-applying structure, and a temperature-sensitive film that allows inductance adjustment by altering the core's geometry, enabling precise inductance tuning without disassembly.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If conventional toroidal inductors are used with fixed inductance, then manufacturing is simple and reliable, but inductance cannot be adjusted in the field requiring scrap or re-winding

Engineering Contradiction:

Improveinductance adjustabilityVSAvoidmanufacturing complexity

Core Design Contradiction:

Adaptability or versatilityVSEase of manufacture

Solution Approach 1:

The inductor transitions from a fixed inductance design to a dynamically adjustable one by incorporating a movable core section that can be repositioned along the winding. This allows the inductance value to be changed in the field by adjusting the position of the core within the toroidal winding, eliminating the need for scrap or re-winding operations.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The toroidal core is divided into two separate sections that can move relative to each other along the winding. This segmentation enables independent adjustment of the core position to achieve different inductance values while maintaining the overall toroidal structure and magnetic circuit integrity.

Inventive Principle:

Principle #1Segmentation

2Adaptability or versatility

If turns are added or removed to adjust inductance, then inductance value changes, but only integer changes are possible and the process is cumbersome

Engineering Contradiction:

Improveinductance tuning rangeVSAvoidadjustment complexity

Core Design Contradiction:

Adaptability or versatilityVSEase of operation

Solution Approach 1:

Instead of discrete integer changes through adding or removing turns, the continuous adjustment is achieved by smoothly moving the core section along the winding. This dynamic positioning allows for fine-tuned inductance changes without the limitations of integer turn adjustments.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The mechanical operation of adding or removing wire turns is replaced by a simpler mechanical adjustment of the core position. This substitution reduces the complexity of the adjustment process from complex wire manipulation to simple core repositioning.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Adaptability or versatility

If windings are repositioned to adjust inductance, then inductance may change, but the effect is negligible and not easily repeatable

Engineering Contradiction:

Improveinductance modification capabilityVSAvoidadjustment repeatability

Core Design Contradiction:

Adaptability or versatilityVSManufacturing precision

Solution Approach 1:

The design enables dynamic adjustment of the core position to precisely control the magnetic path length and thus the inductance value. This provides repeatable and significant inductance changes compared to the negligible effects of winding repositioning.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The inductance is adjusted by changing the geometric parameter of the magnetic circuit (core position) rather than attempting to reposition windings. This parameter change approach provides significant and repeatable inductance adjustments through controlled core movement along the winding.

Inventive Principle:

Principle #35Parameter changes

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

Enables flexible inductance adjustment within a ±10% range, allowing for precise matching and tuning of inductors in field applications, reducing the need for rework and extending the lifespan of tunable trap filters and three-phase matched filters by correcting frequency shifts without replacing capacitors.

Implementation Method 1

a compressible gap material positioned in the gaps... a force-applying structure operable to apply a force to the core to adjust the gaps and thereby an inductance

Methodology Applied

Scientific EffectCompression: Compression

Implementation Method 2

The film is configured to prevent movement of force-applying structure when below a predetermined temperature threshold, and allow movement of the force-applying structure when above the predetermined threshold

Methodology Applied

Scientific EffectThermal response: Thermal Expansion

Data Source

PatentUS11810705B2Adjustable inductor and method of using the same

Publication Date: 2023.11.07 HUBBELL INC

AI summary

An adjustable inductor including a core defining a plurality of gaps, a material positioned in the gaps, at least one winding wound on the core, a force-applying structure, and a film substantially covering the adjustable inductor. The force-applying structure is operable to apply a force to the core to adjust the gaps and thereby an inductance of the adjustable inductor. The film is configured to prevent movement of force-applying structure when below a predetermined temperature threshold, and allow movement of the force-applying structure when above the predetermined threshold.