Inducible component and method for setting an inductivity value for a group of inducible components of the same design

Description

[0001] The present invention relates to an inductive component comprising a coil body with a wire winding. This can be an air coil, i.e., a coil without a magnetic core. For example, the inductive component is used in a stereo system.

[0002] For many applications, a precise adjustment of the component's inductance value, at least as a statistical average for a group of inductors (lot), is desirable. High-precision adjustment of the inductance is particularly necessary for resonant applications.

[0003] The geometric dimensions strongly influence the inductance of electrical components, especially air-core coils. High-precision inductance values ​​can only be manufactured within certain physical limits and require precise control of the geometry. Variations in material properties and operating temperature also lead to variations in the inductance value of inductors with or without ferrite cores. Correcting deviations in the inductance value of a finished component from a desired target value is referred to as "adjustment" or "tuning."

[0004] The publications DE 36 18 122 A1, DE 39 26 231 A1, DE 199 52 192 A1, and DE 10 2008 063 312 A1 describe tunable inductive components. Tuning is usually achieved by pushing a core made of soft magnetic material into or out of the winding, or by pulling or compressing the winding.

[0005] EP 0 461 712 A relates to a transformer having a ferromagnetic core forming a magnetic circuit interrupted by at least one air gap, and a coil former provided with an electrically conductive foil winding package that encloses the core in the region of the air gap. JP H07 240324 A discloses a small transformer. A double-sided adhesive tape is wound around the cylindrical winding portion of a coil, and unwound portions are formed near the flanges of the coil to form barrier spaces. A primary coil is then formed from one winding on the outer circumference of the tape, and further coils are successively formed from windings with double-sided adhesive tapes interposed therebetween, so that other unwound portions can be formed in a similar manner.

[0006] Further inductive components are disclosed in US 2004 / 263307 A1 and US 2003 / 128092 A1.

[0007] It is an object of the present invention to provide an improved inductive component and a method for setting an inductance value for a group of inductive components of the same design.

[0008] According to a first aspect of the present invention, an inductive component according to claim 1 is provided. The coil former comprises a base body, which is at least partially wrapped with an electrically insulating foil. The wrapping with the foil selectively increases the diameter of the coil former. This allows the inductance to be specifically adjusted after winding a winding wire onto the coil former and at least partially over the foil.

[0009] In one embodiment, the base body of the coil former is made of a non-magnetic material. For example, it is a plastic material. Thus, the inductive component can be designed as an air-core coil, i.e., without a magnetic core around which the winding wire is wound. The coil former thus functions purely as a carrier for the winding wire, but not to guide the magnetic flux. In such an embodiment, the inductance is particularly dependent on the geometry, in particular the diameter of the coil, so that precise fine-tuning is possible by changing the diameter.

[0010] For example, the film thickness is significantly less than 1 mm. The film thickness, for example, is a maximum of 100 μm. In particular, the film thickness can be between 10 and 40 μm.

[0011] In an alternative embodiment, the base body can be made of a magnetic material. For example, it can be a ferrite core.

[0012] The foil is wound helically around the base body, for example. The length of the foil, and thus, with a fixed winding geometry, the number of turns of the foil around the base body, can be determined depending on a target inductance value. For example, the number of turns can be varied between one and four.

[0013] The foil is arranged such that the winding wire is arranged over the foil winding. In particular, the geometry of the foil winding corresponds to the geometry of the wire winding, with the foil winding being shorter than the wire winding. The wire winding completely covers the foil lengthwise and extends beyond the foil.

[0014] The winding wire can also completely cover the foil widthwise.

[0015] In the following, the maximum possible effective length is referred to as the length of the foil at which the foil is present underneath the entire winding and thus the entire winding is applied over an enlarged diameter.

[0016] For example, in a first step, the foil is applied to half the possible maximum effective length, then the winding is applied, and the component's inductance is measured. Depending on the measured inductance value, the foil length is then reduced or increased during the production of subsequent components. Initially applying the foil only over a portion of the maximum possible length, for example, over half, is intended to provide scope for fine-tuning the foil length.

[0017] The foil in the resulting component does not extend over the maximum possible effective length of the foil. The foil extends over a maximum of two-thirds of the maximum possible effective length. For example, the foil extends over at least one-third of the length of the base body or the maximum possible effective length.

[0018] Optionally, it is also possible to vary the thickness of the foil or the number of foil layers to adjust the diameter and thus the inductance. The foil can be applied to the base body in a single layer. To further adjust the thickness, the foil can also be applied in multiple layers. To adjust the inductance, for example, a certain number of foil layers is initially present, and then one or more layers are removed or added depending on the measured inductance value. Foils of different thicknesses can also be present, and the foil thickness can be varied for fine-tuning.

[0019] In one embodiment, the foil is made of a non-magnetic material. For example, it can be a plastic material. The foil can be made of the same material as the coil former. Thus, the foil only serves to increase the diameter of the coil former, but not to guide the magnetic flux.

[0020] The coil body may have a recess in which the foil is arranged. The recess is designed for precise positioning of the foil and / or the winding wire.

[0021] The recess is, for example, circumferential; in particular, the recess extends helically around the base body. The recess can only partially circumferentially or continuously circumferentially around the base body. For example, the recess has at least two turns, in particular continuous turns. The recess extends, for example, at least over the entire length of the foil. Preferably, the recess is designed not only for the placement of the foil, but also for the placement of the winding wire. Preferably, the recess extends over a large part of the length of the base body.

[0022] The recess has lateral boundaries so that the foil and / or the winding wire are guided perpendicular to their path in their main direction of extension, preventing them from slipping. The lateral boundaries can be formed by the material of the base body. In particular, the recesses can be formed directly during the manufacture of the base body, for example, in an injection molding process. Only a lateral boundary can be provided for positioning purposes.

[0023] For example, the film is only slightly wider than the recess. The film can also be the same width as the recess or slightly wider than the recess. In this case, the film can be clamped into the recess.

[0024] Because the foil is arranged between the winding wire and the base body in certain areas, along a portion of the length of the winding wire, the outer diameter of the coil body and thus the inner diameter of the winding are enlarged in certain areas. This leads to an increase in the inductance of the component.

[0025] The winding wire is designed, for example, as a flat wire. Alternatively, the winding wire can also be designed as a round wire. It can also be a copper wire.

[0026] The inductance of the component, for example, is between 1 and 1000 nH. Depending on the design, by varying the length of the foil, the inductance can be adjusted within a range of up to 10% of the inductance in 0.1% increments.

[0027] The winding wire extends the entire length of the foil and beyond the length of the foil. The foil and the winding wire are formed, in particular, as two superimposed, uniform windings. The wound winding wire is longer than the foil. Thus, the winding wire only covers a portion of the foil in the main extension direction of the foil. For example, the winding wire extends beyond the foil at both ends.

[0028] The winding wire preferably has more turns than the foil. For example, the number of turns in the foil is a maximum of two-thirds the number of turns in the winding wire. For example, the winding wire has eight turns and the foil has five turns. This provides sufficient flexibility for fine-tuning the inductance.

[0029] The diameter of the wire winding can therefore vary from region to region. In particular, the diameter is larger at the points where the winding wire is arranged above the foil.

[0030] According to one embodiment, the inductive component has a coil former with a recess, wherein the foil and the winding wire are arranged at least partially in the recess. The recess can be designed, in particular, as already described above for the coil former. In particular, the recess can be helical and have at least two turns. The winding wire is, for example, somewhat narrower than the recess. The winding wire can also have the same width as the recess or a slightly larger width than the recess. In this case, the winding wire can be secured in the recess by clamping.

[0031] Alternatively, the foil can also be glued to the base body. For example, the foil is self-adhesive. The foil can also be attached to the base body using an applied adhesive. The winding wire can also be attached to the base body by gluing. It is also possible to first attach the foil to the winding wire, for example, by gluing it to the winding wire, and then arrange and secure the winding wire together with the foil on the base body.

[0032] Alternatively, the winding wire and / or the foil can also be attached to the base body by hot-staking. After inserting the foil and the winding wire into the recess, radially protruding areas of the boundaries can be widened by pressure and heat, so that the foil and the winding wire are at least partially enclosed by the boundaries in the radial direction. Here, too, the foil can be attached first by gluing and then the winding wire can be attached by hot-staking.

[0033] According to a further aspect of the present invention, a method for setting an inductance value for a group of inductive components of the same design is specified according to claim 9. A base body of a coil former is wound at least partially with a foil. The length of the foil is selected depending on a desired inductance value. With a fixed geometry, the length corresponds to one number of turns of the foil.

[0034] The coil former is then wrapped with a winding wire, so that the foil is arranged between the base body and the winding wire in some areas, along a portion of the winding wire. The coil former and the inductive component are designed, for example, as described above.

[0035] To adjust the foil length, the inductance of an inductive component of the same design is measured. The inductance can also be measured indirectly, i.e., using another parameter that represents the inductance. The foil length for another inductive component can then be adjusted depending on the deviation of the measured value from a target value.

[0036] For example, the length is increased or decreased incrementally until the desired target value is reached. For example, the number of turns is changed in a range of 1.00 to 4.00 turns. The length change can be incremented by less than one turn, for example, 0.01 turns.

[0037] According to a further aspect, a coil former for an inductive component has a limitation for positioning a winding wire.

[0038] The boundary is designed, in particular, to guide a section of the winding wire in a central region of the winding, i.e., it is a section adjacent to at least one further turn of the winding wire on both sides. It is therefore not an edge section of the winding. For example, the section is guided by two boundaries on both sides. The boundaries thus form a recess for receiving at least one section of a winding wire.

[0039] The boundary or recess extends, in particular, helically around a base body of the coil former. For example, the boundary or recess has at least two turns. The recess can be formed in a base body of the coil former. The recess can also be designed for positioning a foil as described above. However, the coil former can also have no foil. The coil former can otherwise be designed as described above.

[0040] According to a further aspect, an inductive component comprises such a coil former with a recess in which a winding wire is arranged. The winding wire is designed, for example, as a flat wire. A foil can be arranged between the winding wire and a base body of the coil former. No such foil can also be present. The inductive component can otherwise be designed as described above. For example, the winding wire is attached to the base body by clamping, gluing, or hot-staking, as described above.

[0041] The description of the subject matter specified here is not limited to the individual specific embodiments. Rather, the features of the individual embodiments can be combined with one another—provided that this is technically feasible and falls within the scope of protection of claim 1 or 9.

[0042] In the following, the objects described here are explained in more detail using schematic embodiments.

[0043] They show: Figure 1 shows an embodiment of a coil former in a side view, Figure 2 shows an embodiment of an inductive component in a side view, Figures 3A to 3E show a method for adjusting an inductance in a schematic representation.

[0044] Preferably, in the following figures, like reference numerals refer to functionally or structurally corresponding parts of the various embodiments.

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

[0046] The coil former 1 is designed in particular for an air-core coil, i.e., a coil without a magnetic core. The coil former 1 is non-magnetic. The coil former 1 has, for example, a base body 2 made of plastic. The coil former 1 is manufactured, for example, using an injection molding process. In an air-core coil, the inductance is largely determined by the geometry of the winding.

[0047] In an alternative embodiment, the coil body 1 can also be designed as a magnetic core, for example as a ferrite core, or a magnetic core can be present in the coil body 1.

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

[0049] The base body 2 is partially wrapped with a film 3. The film 3 serves to selectively enlarge the diameter of the base body 2.

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

[0051] The film 3 comprises a non-magnetic material. The film 3 may comprise a plastic material or be made of a plastic material. For example, the coil former 1 and the film 3 may be formed from the same material. In other embodiments, the film 3 may comprise a magnetic material.

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

[0053] Furthermore, the coil former 1 has a recess 4 designed 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 is formed circumferentially around the base body 2. The recess 4 runs, in particular, helically around the base body 2 of the coil body 1. The recess 4 is bordered on both sides by limits 5, 6 perpendicular to the direction of rotation. The limits 5, 6 also run around the base body 2. The recess 4 is thus formed as a circumferential guide groove / channel. In other words, the recess 4 is formed as a thread pitch, and the limits 5, 6 are formed as thread flanks.

[0055] The film 3 is inserted into the recess 4. The film 3 has a similar width to the recess 4. For example, the film 3 is slightly narrower than the recess 4. The film 3 can also be the same width or slightly wider than the recess 4 and can be secured in the recess 4 by clamping or gluing.

[0056] The winding wire 8 (see Figure 2 ) can have a similar width to the recess 4. For example, the width b of the recess 4 is a maximum of 25% larger than the width B of the winding wire.

[0057] The recess 4 has n turns, where n = 8 in this case. Fewer or more than eight turns may be formed. Preferably, the recess has at least two turns.

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

[0059] Figure 2 shows an inductive component 7 comprising a coil body 1 and a winding wire 8 wound around it, which thus forms a winding 9. The coil body 1 can be Figure 1 be executed.

[0060] The winding wire 8 is embodied as a flat wire in this case. The winding wire 8 rests with its main surface on the base body 2 of the coil former 1. Alternatively, the winding wire 8 can also be embodied as a round wire. For example, it is a copper wire.

[0061] In this case, the winding wire 8 has m = 7.50 turns. Thus, the maximum possible effective length of the foil 3 is also 7.50 turns. The winding wire 8 can also have more or fewer turns.

[0062] The winding wire 8 has two ends 10, 11. The ends 10, 11 are, for example, extended to a contact terminal (not shown) for contacting the component 7 or are provided with a further contact (not shown).

[0063] The winding wire 8 is arranged in regions above the foil 3. Thus, the foil 3 is arranged 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 arranged above the foil 3, the diameter of the winding 9 is enlarged. Thus, depending on the length or number of turns k of the foil 3, the winding wire 8 is arranged in regions above the foil 3 and in regions directly on the base body 2. Accordingly, the diameter D of the winding 9 is only enlarged in regions. Depending on the size of the region with an enlarged diameter, the inductance of the component 7 is increased.

[0064] For precise positioning, the winding wire 8 is arranged in the recess 4. The width B of the winding wire 8 is, for example, 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 greater than the width b of the recess 2, so that the winding wire 8 is fastened between the boundaries 5, 6 by clamping. The winding wire 8 can also be fastened in the recess 2 by hot caulking. In particular, radial end regions of the boundaries 5, 6 are widened by hot caulking, so that the winding wire 8 is at least partially enclosed radially outwardly by the end regions.

[0065] In one embodiment, the inductive component 6 has no recesses in the coil body 1 for positioning the winding wire 8, but a foil, as in Figure 1 shown.

[0066] In this case, the winding wire 8 is wound in a single layer on the coil former 1. In other embodiments, the winding wire 8 can also be wound in multiple layers on the coil former 1.

[0067] Instead of a recess 4 with two boundaries 5, 6, only one of the boundaries 5, 6 can be present on one side for positioning. Furthermore, the recess 4 or the boundary 5, 6 can also be formed only in sections. Figures 3A to 3E show process steps for adjusting the inductance of an inductive component. According to Figure 3A A coil body 1 is provided. The coil body 1 can be made of Figure 1 The coil body 1 may, but need not, have the recess 4.

[0068] According to Figure 3BThe length 1 of foil 3 is determined, for example, depending on a target value based on an incoming measured value "M." This information can be obtained from a measurement of the inductance of an identically constructed inductive component. If the measured inductance is smaller than the desired target value, a foil 3 with a longer length 1 than the measured component is selected. If the measured inductance is smaller than the desired target value, a foil 3 with a shorter length 1 than the measured component is selected.

[0069] The length 1 of the foil 3 corresponds to a number of turns k for a given coil body 1 and a given winding geometry. The number of turns k is varied, for example, in increments of 0.01 turns. For example, the number of turns is set in the range from 1.00 to 4.00 turns.

[0070] According to Figure 3CThe foil 3 is wound around the base body 2. In this case, the number of turns is set to approximately 2.05. The foil 3 can also be wound first and then cut to the desired length 1. For precise positioning, the coil body 1 can have the helical recess 4 (see Figure 1 ) and the film 3 can be inserted into the recess 4.

[0071] According to Figure 3DA winding wire 8 is wound around the coil former 1, forming a winding 9. The foil 3 selectively increases the diameter D of the winding 9, as shown schematically here. Depending on the thickness of the foil 3, the diameter of the component 7 is changed, in particular in the μm range. In this case, the winding wire 8 is considerably longer than the foil 3. The winding wire 8 has at least one more turn than the foil 3. For example, 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 high degree of freedom in adjusting the inductance.

[0072] According to Figure 3EAfter applying the winding 9, a measured value M of the inductance is determined. If the inductance is sufficiently close to the target value, the length 1 of the foil 3 is determined for a group of components. If the target value has not yet been reached, the length 1 of the foil 3 is further adjusted based on the measured value M.

[0073] By adjusting the number of turns of foil 3, a highly precise adjustment of the inductance of component 7 can be achieved. For example, depending on the design, the inductance can be adjusted very precisely in 0.1% increments within a range of up to 10%. The target value of the inductance, for example, is between 1 and 1000 nH. List of reference symbols

[0074] 1Coil body 2Base body 3Foil 4Recess 5Limit 6Limit 7Inductive component 8Winding wire 9Winding 10End of the winding wire 11End of the winding wire bWidth of the recess BWidth of the winding wire kNumber of turns of the foil nNumber of turns of the recess mNumber of turns of the winding wire Diameter of the winding MMeasured value

Claims

1. An inductive component comprising: - a coil former, the coil former (1) being configured as a carrier for a winding wire (8), the coil former (1) comprising a base body (2); - an electrically insulating film (3), the base body (2) being wrapped with the electrically insulating film (3) in regions; and - a winding (9) made of a winding wire (8) wrapped around the base body (2), such that the film (3) is disposed between the winding wire (8) and the base body (2) in the radial direction, characterized in that the electrically insulating film (3) extends over a maximum of two thirds of a maximum potential, effective axial length of the film (3) at which the electrically insulating film (3) would be present underneath the entire axial length of the winding (9), such that the winding wire (8) is disposed over the film (3) in regions and directly on the base body (2) in regions along the axial longitudinal extent of the winding (9), and a diameter of the winding (9) is enlarged in the region along the axial longitudinal extent of the winding (9) in which the winding wire is disposed over the film (3).

2. The inductive component according to claim 1, wherein the base body (2) is made of a non-magnetic material.

3. The inductive component according to one of the preceding claims, wherein the film (3) is made of a non-magnetic material.

4. The inductive component according to one of the preceding claims, wherein the film (3) has a maximum thickness of 100 µm.

5. The inductive component according to one of the preceding claims, wherein the coil former (1) comprises a recess (4), wherein the film (3) is disposed in the recess (4).

6. The inductive component according to claim 5, wherein the recess (4) is helical and comprises at least two turns.

7. The inductive component according to one of claims 5 or 6, wherein the winding wire (8) is disposed in the recess (4).

8. The inductive component according to one of the preceding claims, wherein the film (3) is wound helically around the base body (2), and wherein a number of turns (k) of the film (3) is at most two-thirds of a number of turns (m) of the winding wire (8).

9. A method for adjusting an inductance value for a group of inductive components of the same design, a base body (2) of a coil former (1) being wrapped at least in regions with an electrically insulating film (3), the axial length of the film (3) being selected as a function of a target value of the inductance and the coil former (1) then being wrapped with a winding wire (8), such that the film (3) is disposed between the winding wire (8) and the base body (2) in the radial direction at least in regions, and the winding wire (8) is disposed over the film (3) in regions and directly on the base body (2) in regions along the axial longitudinal extent of the winding wire (8), and a diameter of the winding (9) of the winding wire is enlarged along the axial extent (9) in the region in which the winding wire is disposed over the film (3), and wherein, after winding with the winding wire (8), the inductance of the component (7) is measured, and either the length of the film (3) for a further inductive component (7) of otherwise identical design is modified dependent on the deviation of the measured value from a target value, if the target value has not yet been reached, wherein if the measured inductance is less than the target value then a film (3) having a greater length than for the measured component (7) is selected for the further inductive component (7), or if the measured inductance is greater than the target value then a film (3) having a lesser length than the measured component (7) is selected, or otherwise the length of the film (3) is defined for the group of components when the target value is reached.

10. The method according to claim 9, wherein the film (3) is wrapped helically around the base body (2) and wherein the length (1) of the film (3) is varied in steps less than one turn of the film (3) around the coil former (1).