US-12621909-B2 - Coil former, inductive component and method for adjusting an inductance

US12621909B2US 12621909 B2US12621909 B2US 12621909B2US-12621909-B2

Abstract

An inductive component is provided, including: a coil former including a base body and being a carrier for a winding wire; an electrically insulating foil, some regions of the body being wrapped with the foil; and a winding of the wire around the coil former, such that the foil is between the wire and the body, and extends over a maximum of two thirds of a maximum possible effective length of the foil with which the foil would be present underneath the entire winding such that in some regions the wire is disposed over the foil, and in some regions the wire is disposed directly on the body, and such that a diameter of the winding in a region in which the wire is disposed over the foil is increased. A method for adjusting an inductance value for a group of inductive components of a same design is also provided.

Inventors

Oleg FURSA
Jürgen Frey
Stefan Weber

Assignees

PHILIP MORRIS PRODUCTS S.A.

Dates

Publication Date: 20260505
Application Date: 20200527
Priority Date: 20190529

Claims (14)

1 . An inductive component, comprising: a coil former comprising a base body and being configured as a carrier for a winding wire; an electrically insulating foil, wherein some regions of the base body are wrapped with the electrically insulating foil; and a winding of the winding wire, which is wound around the coil former, such that the electrically insulating foil is entirely disposed between the winding wire and the base body, wherein the electrically insulating foil extends over a maximum of two thirds of a maximum possible effective length of the electrically insulating foil, wherein the maximum possible effective length of the electrically insulating foil is the length of the electrically insulating foil with which the electrically insulating foil is present underneath the entire winding, with which the electrically insulating foil would be present underneath the entire winding such that in some regions the winding wire is disposed over the electrically insulating foil, and in some regions the winding wire is disposed directly on the base body, and such that a diameter of the winding in a region in which the winding wire is disposed over the electrically insulating foil is increased compared to a diameter of the winding where the winding wire is disposed directly on the base body.
2 . The inductive component according to claim 1 , wherein the base body is made of a non-magnetic material.
3 . The inductive component according to claim 1 , wherein the electrically insulating foil is made of a non-magnetic material.
4 . The inductive component according to claim 1 , wherein the electrically insulating foil has a maximum thickness of 100 μm.
5 . The inductive component according to claim 1 , wherein the coil former further comprises a recess, and wherein the electrically insulating foil is disposed in the recess.
6 . The inductive component according to claim 5 , wherein the recess is helical and comprises at least two turns.
7 . The inductive component according to claim 5 , wherein the winding wire is disposed in the recess.
8 . The inductive component according to claim 1 , wherein the electrically insulating foil is wrapped helically around the base body, and wherein a number of turns (k) of the electrically insulating foil is at most two thirds of a number of turns (m) of the winding wire.
9 . The inductive component according to claim 1 , wherein an outermost diameter of the winding wire is greater than an outermost diameter of the electrically insulating foil that the winding wire is wound around.
10 . The inductive component according to claim 1 , wherein the electrically insulating foil extends over at least one third of the maximum possible effective length.
11 . The inductive component according to claim 1 , wherein a thickness of the electrically insulating foil is varied along a length of the electrically insulating foil.
12 . The inductive component according to claim 1 , wherein a number of layers of the electrically insulating foil is varied along a length of the electrically insulating foil.
13 . A method for adjusting an inductance value for a group of inductive components of a same design, the method comprising: wrapping at least some regions of a base body of a coil former with an electrically insulating foil, wherein a length of the electrically insulating foil is selected as a function of a target value of the inductance value; after the wrapping of the at least some regions of the base body of the coil former with the electrically insulating foil is complete, wrapping the coil former with a winding wire, such that the electrically insulating foil is entirely disposed at least in some regions between the winding wire and the base body; measuring an inductance of the inductive components after the wrapping with the winding wire; and either: changing a length of the electrically insulating foil for a further inductive component as a function of a deviation of a measured value from a target value, if the target value has not yet been reached, or selecting a foil with a greater length than the measured inductive components for the further inductive component, if the measured inductance is smaller than a desired target value, or selecting a foil with a shorter length than the measured inductive components, if the measured inductance is larger than a desired target value, or defining a length of the foil for the group of inductive components, if the target value is reached; wherein the electrically insulating foil extends over a maximum of two thirds of a maximum possible effective length of the electrically insulating foil, wherein the maximum possible effective length of the electrically insulating foil is the length of the electrically insulating foil with which the electrically insulating foil is present underneath the entire winding, with which the electrically insulating foil would be present underneath the entire winding such that in some regions the winding wire is disposed over the electrically insulating foil, and in some regions the winding wire is disposed directly on the base body, and such that a diameter of the winding in a region in which the winding wire is disposed over the electrically insulating foil is increased compared to a diameter of the winding where the winding wire is disposed directly on the base body.
14 . The method according to claim 13 , wherein the electrically insulating foil is wrapped helically around the base body, and wherein the changing the length of the electrically insulating foil for the further inductive component includes varying the length in steps smaller than one turn of the electrically insulating foil around the coil former.

Description

The present invention relates to a coil former for an inductive component and an inductive component comprising a coil former with a wire winding. This can be an air-core coil, i.e. a coil without a magnetic core. The inductive component is used in a stereo system, among other things. For many applications, a precise adjustment of the inductance value of the component, at least on a statistical average for a group of inductances (lot), is desirable. Resonance applications in particular require a highly precise adjustment of the inductance. The geometric dimensions strongly affect the inductance of electrical components, in particular in the case of air-core coils. Highly precise inductance values can only be produced within certain physical limits and require precise control of the geometry. For inductances with or without a ferrite core, variations in the material properties and the operating temperature lead to a variation of the inductance value as well. The correction of deviations of the inductance value of a finished component from a desired target value is referred to as “adjustment” or “tuning”. Documents DE 36 18 122 A1, DE 39 26 231 A1, DE 199 52 192 A1 and DE 10 2008 063 312 A1 describe adjustable inductive components. An adjustment is usually accomplished by pushing a core of soft magnetic material into or out of the interior of the winding, or by pulling apart or compressing the winding. It is an object of the present invention to provide an improved coil former, an improved inductive component and a method for adjusting an inductance of an inductive component. According to a first aspect of the present invention, a coil former is configured as a carrier for a winding wire of an inductive component. The coil former comprises a base body, of which at least some regions are wrapped with an electrically insulating foil. The diameter of the coil former is selectively increased by the wrapping with the foil. The inductance can thus be adjusted in a targeted manner after a winding wire has been wound onto the coil former and over at least some regions of the foil. In one embodiment, the base body of the coil former is made of a non-magnetic material. This can be a plastic material, for example. The inductive component can thus be configured as an air-core coil, i.e. not comprise a magnetic core around which the winding wire is wound. The coil former thus functions purely as a carrier for the winding wire and does not guide the magnetic flux. In such an embodiment, the inductance is particularly strongly dependent on the geometry, in particular the diameter of the coil, so that precise fine tuning by changing the diameter is possible. For example, the thickness of the foil is significantly less than 1 mm. The maximum thickness of the foil is 100 μm, for example. The thickness of the foil can in particular be between 10 and 40 μm. In an alternative embodiment, the base body can be made of a magnetic material. This can be a ferrite core, for example. The foil is, for example, wrapped helically around the base body. The length of the foil and, if the geometry of the wrapping is fixed, thus also the number of turns of the foil around the base body can be defined as a function of a target value of the inductance. For example, the number of turns is varied between one turn and four turns. The foil is in particular arranged in such a way that the winding of the winding wire can be disposed over the wrapping of the foil. The geometry of the wrapping of the foil in particular corresponds to the geometry of the winding of the wire, wherein the wrapping of the foil is preferably shorter than the winding of the wire. The wire winding can cover the entire length of the foil and extend beyond the foil. The winding wire can also cover the entire width of the foil. In the following, the maximum possible effective length is the length of the foil with which the foil is present underneath the entire winding. The entire winding is thus applied over an enlarged diameter. The foil is applied to half the possible maximum effective length in a first step, for example, then the winding is applied and the inductance of the component measured. The length of the foil is then reduced or increased for the production of further components as a function of the measured inductance value. The initial application of the foil over only part of the maximum possible length, for example over half, is intended to provide flexibility for fine tuning the length of the foil. The foil in the resulting component does not extend over the entire length of the base body, for example, in particular not over the maximum possible, effective length of the foil. For example the foil extends over no more than two thirds of the length of the base body or the maximum possible, effective length. Or the foil extends over at least a third of the length of the base body or the maximum possible, effective length. It is also possible for the foil to extend over