COIL FORMER, INDUCTIVE COMPONENT AND METHOD FOR ADJUSTING AN INDUCTANCE

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.

Claims

1.-16. (canceled)

17. 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 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 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.

18. The inductive component according to claim 17, wherein the base body is made of a non-magnetic material.

19. The inductive component according to claim 17, wherein the electrically insulating foil is made of a non-magnetic material.

20. The inductive component according to claim 17, wherein the electrically insulating foil has a maximum thickness of 100 μm.

21. The inductive component according to claim 17, wherein the coil former further comprises a recess, and wherein the electrically insulating foil is disposed in the recess.

22. The inductive component according to claim 21, wherein the recess is helical and comprises at least two turns.

23. The inductive component according to claim 21, wherein the winding wire is disposed in the recess.

24. The inductive component according to claim 17, 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.

25. 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; wrapping the coil former with a winding wire, such that the electrically insulating foil is 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.

26. The method according to claim 25, wherein the electrically insulating foil is wrapped helically around the base body, and wherein a length (l) of the electrically insulating foil is varied in steps smaller than one turn of the electrically insulating foil around the coil former.

Description

[0040] The figures show:

[0041] FIG. 1 an embodiment of a coil former in a lateral view,

[0042] FIG. 2 an embodiment of an inductive component in a lateral view,

[0043] FIGS. 3A to 3E a method for adjusting an inductance in a schematic illustration.

[0044] In the following figures, the same reference signs preferably refer to functionally or structurally equivalent parts of the various embodiments.

[0045] FIG. 1 shows a coil former 1 for an inductive component. The coil former 1 is configured as a carrier for a winding wire.

[0046] The coil former 1 is in particular configured for an air-core coil, i.e. a coil in which there is no magnetic core. The coil former 1 is non-magnetic. The coil former 1 may comprise a base body 2 made of plastic. The coil former 1 is produced in an injection molding process, for example. The inductance of an air-core coil is largely determined by the geometry of the winding.

[0047] In one alternative embodiment, the coil former 1 can also be configured as a magnetic core, for example as a ferrite core, or there may a magnetic core in the coil former 1.

[0048] The base body 2 in the present case has a cylindrical shape. The base body 2 can also have a different shape, for instance a cuboid shape. The base body 2 can also be a part of a larger body, for example an annular body. The base body 2 can be configured as a hollow body.

[0049] Some regions of the base body 2 are wrapped with a foil 3. The foil 3 serves to selectively increase the diameter of the base body 2.

[0050] The foil 3 is thin, which allows fine tuning of the diameter of the base body 2 and thus of the inductance of the component after a winding wire is wound over the foil 3. The foil 3 is between 10 μm and 40 μm thick, for example. For instance, the foil 3 is 25 μm thick. In the present case, the foil 3 is applied in one layer.

[0051] The foil 3 comprises a non-magnetic material. The foil 3 can comprise a plastic material or be made of a plastic material. The coil former 1 and the foil 3 can, for example, be made of the same material. In other embodiments, the foil 3 can comprise a magnetic material.

[0052] By selectively changing the length of the foil 3, corresponding to the number of turns k, the region with the increased diameter can be adjusted selectively, thus allowing the inductance of the resulting component to be tuned. In the present case, the foil 3 extends over k=2.00 turns. For example, the number of turns of the foil 3 is varied in a range of k=1.00 to 4.00 turns. The variation is carried out in increments of 0.01 turns, for example.

[0053] The coil former 1 furthermore comprises a recess 4, which is configured for the precise positioning of the foil 3 and/or the winding wire 8. The more precisely the foil 3 and/or the winding wire 8 can be positioned on the coil former 1, the more precisely the inductance of the component can be adjusted.

[0054] The recess 4 extends circumferentially around the base body 2. The recess 4 extends in particular helically around the base body 2 of the coil former 1. The recess 4 is delimited on both sides perpendicular to the circumferential direction by the limitations 5, 6. The limitations 5, 6 likewise extend around the base body 2. The recess 4 is thus configured as a circumferential guide groove/channel. In other words, the recess 4 is configured as a thread and the limitations 5, 6 are configured as thread flanks.

[0055] The foil 3 is placed into the recess 4. The width of the foil 3 is similar to that of the recess 4. The foil 3 may be slightly narrower than the recess 4. The foil 3 can also be the same width or slightly wider than the recess 4 and be fixed in the recess 4 by clamping or gluing.

[0056] The winding wire 8 (see FIG. 2) can also have a width similar to that of the recess 4. For instance, the width b of the recess 4 is at most 25% greater than the width B of the winding wire.

[0057] The recess 4 comprises n turns, whereby in the present case n=8. There can also be less or more than eight turns. The recess preferably comprises at least two turns.

[0058] In an alternative embodiment, the coil former 1 does not have a recess 4 for positioning the winding wire, but does have a foil 3.

[0059] In a further alternative embodiment, the coil former 1 does not have a foil for increasing the diameter, but does have a recess 4 for precisely positioning the winding wire.

[0060] FIG. 2 shows an inductive component 7 comprising a coil former 1 and a winding wire 8 wound around it, which thus forms a winding 9. The coil former 1 can be designed according to FIG. 1.

[0061] In the present case, the winding wire 8 is configured as a flat wire. The primary surface of the winding wire 8 rests on the base body 2 of coil former 1. The winding wire 8 can alternatively also be configured as a round wire. This is a copper wire, for example.

[0062] The winding wire 8 in the present case comprises m=7.50 turns. The maximum possible, effective length of the foil 3 is thus likewise 7.50 turns. The winding wire 8 can also have more or fewer turns.

[0063] The winding wire 8 comprises two ends 10, 11. The ends 10, 11 are continued on, for example to connect the component 7 to a contact terminal (not shown), or provided with a further contact connection (not shown).

[0064] Some regions of the winding wire 8 are disposed over the foil 3. The foil 3 is thus disposed between the base body 2 of the coil former 1 and the winding wire 8. In the region in which the winding wire 8 is disposed over the foil 3, the diameter of the winding 9 is increased. The winding wire 8 is thus disposed over the foil 3 in some regions, and directly on the base body 2 in some regions, depending on the length or number of turns k of the foil 3. The diameter D of the winding 9 is therefore increased only in some regions. The inductance of the component 7 is increased as a function of the size of the region with the increased diameter.

[0065] The winding wire 8 is disposed in the recess 4 for precise positioning. The width B of the winding wire 8 may be only slightly less than the width b of the recess 4. The position of the winding wire 8 is thus precisely determined by the recess 4. The width B of the winding wire 8 can also be slightly larger than the width b of the recess 2, so that the winding wire 8 is fixed between the limitations 5, 6 by clamping. The winding wire 8 can also be fixed in the recess 2 by hot caulking. Radial end regions of the limitations 5, 6 are in particular widened by hot caulking, so that the winding wire 8 is at least partially enclosed radially outward by the end regions.

[0066] In one embodiment, the inductive component 6 does not have recesses in the coil former 1 for positioning the winding wire 8, but does have a foil, as shown in FIG. 1.

[0067] In the present case, the winding wire 8 is wound onto the coil former 1 in one layer. In other embodiments, the winding wire 8 can also be wound onto the coil former 1 in multiple layers.

[0068] In an alternative embodiment, the inductive component 7 does not have a foil between the base body 2 and the winding wire 8, but does have the recess 4 for precisely positioning the winding wire 8. In this case, the diameter D of the winding 9 is uniform. Instead of a recess 4 with two limitations 5, 6, there can also only be one limitation 5, 6 for positioning on one side. The recess 4 or the limitation 5, 6 can furthermore also only be configured in sections.

[0069] FIGS. 3A to 3E show method steps for adjusting an inductance of an inductive component.

[0070] According to FIG. 3A, a coil former 1 is provided. The coil former 1 can be configured like the coil former 1 of FIG. 1. The coil former 1 can, but not does not have to, comprise the recess 4.

[0071] According to FIG. 3B, the length l of the foil 3 is defined, for example as a function of a target value, on the basis of an input measured value “M”. The information can be obtained from a measurement of the inductance from an identical inductive component. If the measured inductance is smaller than a desired target value, a foil 3 with a greater length l than the measured component is selected. If the measured inductance is smaller than a desired target value, a foil 3 with a shorter length l than the measured component is selected.

[0072] The length l of the foil 3 corresponds to a number of turns k for a specified coil former 1 and a specified winding geometry. The number of turns k is varied in increments of 0.01 turns, for example. The number of turns is adjusted in the range from 1.00 to 4.00 turns, for example.

[0073] According to FIG. 3C, the foil 3 is wrapped around the base body 2. In the present case, the number of turns is set to approximately 2.05. The foil 3 can also be wrapped first and then cut to the desired length l. For precise positioning, the coil former 1 can comprise the helical recess 4 (see FIG. 1) and the foil 3 can be placed into the recess 4.

[0074] According to FIG. 3D, a winding wire 8 is wound around the coil former 1, so that a winding 9 is formed. The foil 3 selectively increases the diameter D of the winding 9, as shown here schematically. The diameter of the component 7 is changed as a function of the thickness of the foil 3, in particular in the μm range. The winding wire 8 in the present case is substantially longer than the foil 3. The winding wire 8 comprises at least one turn more than the foil 3. For instance, the number of turns of the winding wire 8 is at least one third greater than the number of turns k of the foil 3. This allows a large degree of freedom for adjusting the inductance.

[0075] According to FIG. 3E, a measured value M of the inductance is determined after the application of the winding 9. If the inductance is sufficiently close to the target value, the length l of the foil 3 is defined for a group of components. If the target value has not yet been reached, the length l of the foil 3 is changed further on the basis of the measured value M.

[0076] By adjusting the number of turns of the foil 3, a highly precise adjustment of the inductance of the component 7 can be achieved. For instance, depending on the design, the inductance can be adjusted very precisely in 0.1% increments in a range of up to 10%. The target value of the inductance is between 1 and 1000 nH, for example.

LIST OF REFERENCE SIGNS

[0077] 1 Coil former [0078] 2 Base body [0079] 3 Foil [0080] 4 Recess [0081] 5 Limitation [0082] 6 Limitation [0083] 7 Inductive component [0084] 8 Winding wire [0085] 9 Winding [0086] 10 End of the winding wire [0087] 11 End of the winding wire [0088] b Width of the recess [0089] B Width of the winding wire [0090] k Number of turns of the foil [0091] n Number of turns of the recess [0092] m Number of turns of the winding wire [0093] D Diameter of the winding [0094] M Measured value