EP3747032B1 - Core for an inductive component, and inductive component - Google Patents

Description

The invention relates to a core for an inductive component with at least a first side part, a middle part and a second side part, the middle part having a central section, a first edge section which is arranged parallel to the central section, and a second edge section which is parallel to the central portion is arranged, wherein the central portion is arranged between the first and the second edge portion. The invention also relates to an inductive component having a core according to the invention.

Cores for inductive components are made in a wide variety of shapes.

Cores, for example, whose side parts generally have the cross-sectional shape of a capital letter E, can be produced and processed automatically. In the context of this cross-sectional shape, the side parts can have special geometric characteristics and are then referred to, for example, as E-cores, PQ-cores, ETD-cores, RM-cores, etc. If corresponding side parts are to be wound with comparatively long bobbins, middle parts are used, which then usually have the shape of two side parts placed against one another with their rear sides. In such middle parts, a central section, for example circular cylindrical, a first edge section, which is arranged parallel to the central section, and a second edge section is provided, which is constructed symmetrically to the first edge section and is also arranged parallel to the central section. So that such middle parts can withstand the considerable mechanical loads to which inductive components with such cores are exposed, for example up to ten times the acceleration due to gravity, the first edge section, the central section and the second edge section of the middle parts can be connected to one another by means of a central web. Such a central web would be made in one piece with the central part and the two edge sections, so that the central part forms a stable unit and can be mechanically loaded to the same extent as the side parts. From a magnetic point of view, the central bar forms a shunt. Stray capacitance results between two coils of an inductive component.

EP 2 924 697 A1 and DE 20 2011 051056 U1 each describe an inductive component with a core and two windings.

The invention is intended to improve a core for an inductive component and an inductive component that can be produced and processed in an automated manner.

According to the invention, a core with the features of claim 1 is provided for this purpose. Advantageous further developments of the invention emerge from the subclaims.

A core according to the invention for an inductive component has at least a first side part, a middle part and a second side part, the middle part having a central section, a first edge section which is arranged parallel to the central section, and a second edge section which is parallel to the central section Section is arranged, wherein the central portion is arranged between the first and the second edge portion. At least one plastic component is provided, which is provided at least between the central section and the first edge section and / or at least between the central section and the second edge section, in order to set a stray capacitance of the inductive component and to influence a secondary magnetic flux of the inductive component.

By providing the plastic component, the electrical properties and, in particular, the resonance frequency of an inductive component provided with the core according to the invention can be set. This is done by suitable selection of the dielectric constant ε _r of the plastic used for the plastic component. Compared to conventional cores for inductive components, in which the central section is connected to the first edge section and the second edge section by means of a ferrite web, the secondary magnetic flux from the central section to the two edge sections can also be significantly reduced and, with a suitable selection of the material of the plastic component, even can be completely prevented. In addition, the plastic component can of course also ensure mechanical stabilization of the core in that it forms a mechanical connection between the central section and the first edge section and the second edge section, and in this regard acts as a positioning component.

In a further development of the invention, a dielectric constant ε _{r of} the plastic component is in the range from 1 to 50, in particular in the range from 1 to 10.

In this way, the stray capacitance of an inductive component provided with the core according to the invention can be set within wide limits and thus a resonance frequency of such an inductive component can also be changed within wide limits.

In a further development of the invention, the plastic component fixes the first edge section and the second edge section in a defined position relative to one another.

In this way, the central section and the two edge sections can be securely fixed to one another and thereby also withstand high mechanical loads. The fixation of the central section and the two edge sections in a defined relative position to each other also allows the automatic processing of the core according to the invention to form an inductive component.

In a further development of the invention, the plastic component surrounds the central section of the middle part at least over part of the length of the central section.

In this way, stable mechanical fixation of the central section can be achieved.

According to the invention, the plastic component is formed from a plastic with a low relative magnetic permeability.

In this way it can be ensured that a magnetic shunt through the plastic component is negligible. The relative permeability µ _r is then 1 or is in the range of about 1.

In a further development of the invention, the plastic component is made of silicone, polyamide, isoprene or latex.

In a further development of the invention, the plastic of the plastic component has, as an admixture, carbon, glass granulate, a ceramic compound or ceramic compound and / or viscose. On the one hand, a plastic component ensures a high mechanical load capacity of the core, which equals or even exceeds the mechanical load capacity of one-piece middle parts of conventional cores. With regard to the magnetic properties of the core according to the invention, a magnetic shunt through the plastic component can be completely or at least almost completely avoided. Depending on the selection of the plastic used, if a defined magnetic shunt is desired, the size of this magnetic shunt can be set. With regard to the magnetic properties of such a core or such an inductive component, the invention achieves a considerable improvement. With regard to the electrical properties of the core according to the invention, the electrical properties can also be set in a defined manner by selecting a suitable plastic. The plastic component can advantageously be produced by means of injection molding or a hotmelt or melt adhesive process.

In a further development of the invention, the plastic component is designed as a plate-shaped web which is perpendicular to the central section, the first edge section and the second Edge portion is arranged and which has three through openings for receiving the central portion, the first edge portion and the second edge portion.

In this way, the central section and the two edge sections can be attached to the plastic component in a very simple manner. In particular, automated production of the middle part is possible.

In a further development of the invention, a first of the three through openings is adapted to the cross section of the central section of the central part, a second of the three through openings to the cross section of the first edge section of the central part and a third of the three through openings to the cross section of the second edge section of the central part.

In this way, the central section and the two edge sections can be securely fixed in the plastic component.

In a further development of the invention, the middle part, the first edge section and / or the second edge section are fixed in a clamping manner in the respective through opening of the plastic component.

In this way, the middle part and the two edge sections can be fixed in the plastic component by simply pushing the middle part and the two edge sections into the through openings of the plastic component.

In a further development of the invention, the first side part and the second side part generally have a cross section similar to the shape of the letter E.

Such side parts of cores are referred to, for example, as E cores, PQ cores, ETD cores, RM cores etc. and are very advantageous in terms of their mechanical, electrical and magnetic properties. Such cores can also be produced in an automated manner and processed in an automated manner, in particular wound and completed to form inductive components.

In a further development of the invention, the plastic component has a base plate from which a plate-shaped web protrudes perpendicularly, the base plate being provided for fixing the first side part and the second side part of the core.

In this way, by means of the plastic component in its function as a positioning component, not only the middle part with the central section and the two edge sections, but also the the two side parts of the core are also fixed. This is extremely advantageous in particular with regard to the automated production of an inductive component with the core according to the invention.

In a further development of the invention, the base plate is provided with fixing means, in particular latching means or clamping means, on its side facing away from the plate-shaped web.

Such fixing means can be used to fasten the core or a finished inductive component with the core according to the invention.

The problem on which the invention is based is also solved by an inductive component with a core according to the invention, the inductive component having at least one coil which surrounds the central section of the middle part at least in sections.

Such an inductive component has the same mechanical load capacity as inductive components with conventional cores, but has the considerable advantage in magnetic terms that no magnetic shunt is caused by the middle part or a magnetic shunt can be set in a defined manner by suitable selection of a plastic for the plastic component can. In addition, the inductive component can be produced in a fully automated manner.

In a further development of the invention, a dielectric constant of the plastic of the plastic component is matched to an inductance of the coil in order to obtain a defined resonance frequency of the inductive component.

The dielectric constant ε _r can be set by selecting the plastic of the plastic component. For example, when using silicone ε _r = 2.9, when using polyamide ε _r = 1.7, when using isoprene ε _r = 2.1 and when using latex ε _r = 24 is achieved. If the plastic of the plastic component is provided with admixtures such as carbon, glass granulate, ceramic compounds or viscose, the dielectric constant of the plastic can be set in still further ranges. For example, carbon has ε _r = 2.5, glass granulate ε _r = 4.0, ceramic compound ε _r = 17 and viscose ε _r = 34.5.

Particularly with regard to the electrical properties of the inductive component, the invention thus offers considerable advantages over conventional inductive components. the According to the invention, the resonance frequency of the inductive component can be set so that the working range of the inductive component can be changed flexibly.

Fig. 1

ein erfindungsgemäßes induktives Bauelement von schräg oben,

Fig. 2

eine Darstellung des Kerns des induktiven Bauelements der Fig. 1,

Fig. 3

den Kern der Fig. 2, wobei das Kunststoffbauteil des Kerns weggelassen wurde,

Fig. 4

eine Darstellung des induktiven Bauelements der Fig. 1, wobei vom Mittelteil des Kerns der zentrale Abschnitt und die beiden Randabschnitte nicht dargestellt sind,

Fig. 5

das induktive Bauelement der Fig. 4, wobei das Kunststoffbauteil des Kerns nicht dargestellt ist,

Fig. 6

das Mittelteil des Kerns der Fig. 2,

Fig. 7

das Kunststoffbauteil des Kerns der Fig. 2,

Fig. 8

einen plattenförmigen Steg des Kunststoffbauteils der Fig. 7,

Fig. 9

den plattenförmigen Steg der Fig. 8 in einer Ansicht von vorne,

Fig. 10

eine Grundplatte des Kunststoffbauteils der Fig. 7 und

Fig. 11

eine Darstellung eines vereinfachten elektrischen Ersatzschaltbildes eines erfindungsgemäßen induktiven Bauelements.

Further features and advantages of the invention emerge from the claims and the following description of a preferred embodiment of the invention in conjunction with the drawings. In the drawings show:

Fig. 1

an inventive inductive component obliquely from above,

Fig. 2

an illustration of the core of the inductive component of FIG Fig. 1 ,

Fig. 3

the core of the Fig. 2 with the plastic component of the core omitted,

Fig. 4

a representation of the inductive component of Fig. 1 , the central section and the two edge sections of the middle part of the core not being shown,

Fig. 5

the inductive component of the Fig. 4 , whereby the plastic component of the core is not shown,

Fig. 6

the middle part of the core of the Fig. 2 ,

Fig. 7

the plastic component of the core of the Fig. 2 ,

Fig. 8

a plate-shaped web of the plastic component of the Fig. 7 ,

Fig. 9

the plate-shaped web of the Fig. 8 in a view from the front,

Fig. 10

a base plate of the plastic component of the Fig. 7 and

Fig. 11

a representation of a simplified electrical equivalent circuit diagram of an inductive component according to the invention.

Fig. 1 shows an inventive inductive component 10 in a view obliquely from above. The inductive component 10 has a core 12 and two coils 14, 16. The two coils 14, 16 are each wound from flat wire with a rectangular cross section, one narrow side of the rectangular cross section pointing towards the central longitudinal axis of the two coils 14, 16.

The core 12 has a first side part 18, a second side part 20 and a middle part 22. The two side parts 18, 20 are designed identically and have the shape of a so-called PQ core. Seen in cross section, a section plane then in Fig. 1 would run halfway up the inductive component 10 and containing the central longitudinal axis of the two coils 14, 16, the two side parts 18, 20 have the cross-sectional shape of a capital letter E. A central section 24 has a circular cylindrical shape and is thus adapted to the internal shape of the two coils 14, 16. The two edge sections 26, 28 each have a flat outer surface and a convexly curved inner surface, which in turn is adapted to the outer shape of the two coils 14, 16.

The middle part 22 has a central section 30 as well as a first edge section 32 and a second edge section 34 and a plastic component 36. The two edge sections 32, 34 are designed to be identical to one another and each have a flat rear side and a convexly curved inner side. The convexly curved inner sides are each adapted to the outer shape of the two coils 14, 16. The two edge sections 32, 34 each connect the edge sections 26, 28 of the two side parts 18, 20 and essentially continue their shape. In Fig. 1 the edge sections 32, 34 and the side parts 18, 20 are shown in simplified form. In reality, the side surfaces of the edge sections 32, 34 and the side parts 18, 20 can be aligned, that is to say merge into one another without a step.

The central section 30 has a circular cylindrical design and connects the central sections 24 of the two side parts 18, 20.

An illustration of the core 12 of the inductive component 10 of FIG Fig. 1 is in a view obliquely from above in Fig. 2 shown. The core 12 has the two side parts 18, 20 and the middle part 22. As in Fig. 2 can be clearly seen, the middle part 22 connects the two side parts 18, 20.

The two side parts 18, 20 consist, for example, of a ferrite material and are each made in one piece. In the middle part 22, the central section 30 and the two edge sections 32, 34 are made of ferrite material. The plastic component 36 or positioning component consists of a plastic, for example silicone or polyamide.

There is no measurable air gap between the abutting end faces of the two side parts 18, 20 and the middle part 22, since the two side parts 18, 20 rest on the respectively assigned end faces of the central section 30 or the first edge section 32 and the second edge section 34 . From a magnetic point of view, however, it is a minor one There is an air gap, which is caused by slight unevenness in the respective end faces. To set the magnetic properties of the inductive component 10, an air gap between the two side parts 18, 20 and the middle part 22 can also be deliberately set. A gap that is produced by inserting a plastic plate between the two side parts and the middle part 22 is also referred to as an air gap.

Fig. 3 shows only the components of the core 12 made of ferrite material, namely the two side parts 18, 20 and the central section 30 as well as the first edge section 32 and the second edge section 34 of the middle part.

Fig. 4 shows the inductive component 10 of FIG Fig. 1 , wherein the central portion and the first edge portion and the second edge portion have been omitted from the central portion. It can already be seen in this view that the plastic component 36 has a plate-shaped web 38 which protrudes perpendicularly from a base plate 40. Both the plate-shaped web 38 and the base plate 40 are made of a plastic. The plate-shaped web 38 has a total of three through openings 42, 44 and 46. The second through opening 44 has a circular cylindrical design and is adapted to the cross section of the central section 30. The first through opening 42 and the third through opening 46 are adapted to the cross section of the first edge section 32 and the second edge section 34, respectively.

The through openings 42, 44, 46 are each designed so that the central section 30 is clamped in the second through opening 44, that the first edge section 32 is clamped in the first through opening 42 and that the second edge section 34 is clamped in the third through opening 46 is included, cf. Fig. 1 . By means of the plastic component 36 in its function as a positioning component, the central section 30, the first edge section 32 and the second edge section 34 can be fixed relative to one another.

The base plate 40 can in turn be used to position and fix the two side parts 18, 20 relative to one another and relative to the central part of the core, specifically to the plate-shaped web 38 of the plastic component 36.

On an in Fig. 4 Unrecognizable underside of the base plate 40, fixing means, for example latching means, can be provided in order to fasten the finished inductive component to a carrier, for example a housing or also a printed circuit board.

Fig. 5 shows only the two side parts 18, 20 with the two coils 14, 16. The coil 14 partially surrounds the middle section of the first side part 18 and the coil 16 partially surrounds the middle section of the second side part 20. In the view of Fig. 5 it can also be clearly seen that the convex inner sides of the edge sections 26, 28 are adapted to the outer shape of the coils 14 and 16, respectively.

Fig. 6 shows the central part 22 of the core of FIG Fig. 2 with the plastic component 36, which has the plate-shaped web 38 and the base plate 40. The first edge section 32, the central section 30 and the second edge section 34 of the middle part 22 are fixed in a clamping manner in the through openings of the plate-shaped web 38.

Fig. 7 shows the plastic component 36 alone. The plate-shaped web 38 is received in a groove 50 in the base plate 40, which is shown in FIG Fig. 10 can be seen. The dimensions of the groove 50 are adapted to the dimensions, specifically the thickness of the plate-shaped web 38, so that the plate-shaped web 38 is received in the groove 50 in a clamping manner, for example.

The representations of the Fig. 8 and Fig. 9 show the plate-shaped web 38 alone from two different angles.

With the core 12 according to the invention or the inductive component 10 according to the invention, it is possible to provide an inductive component that can be produced in an automated manner and also processed in an automated manner. Such an inductive component according to the invention is mechanically the same or even more resilient than conventional inductive components with a central part made in one piece from ferrite. From a magnetic point of view, a shunt in the middle part can be prevented by the plastic component 36 made of plastic, especially the plate-shaped web 38. With a suitable selection of the plastic, the size of a magnetic shunt can be set to a desired value through the plate-shaped web 38 of the plastic component 36. For this purpose, ferrite powder can be mixed with a plastic during the production of the plate-shaped web 38, for example.

From an electrical point of view, the properties of the inductive component according to the invention can also be set by the selection of the plastic for the plate-shaped web 38 of the plastic component 36. The size of a parasitic stray capacitance can be adjusted by the dielectric constant of the plastic of the plate-shaped web 38 and can be used, for example, to shift the resonance frequency point of the inductive component 10 be used. Ultimately, this leads to different impedance curves over the frequency

Fig. 11 shows a simplified equivalent circuit diagram of an inductive component according to the invention. The equivalent circuit has two branches connected in parallel to one another. The right branch initially shows the inductance L, which is determined by the parameters of the coils used, including the number of turns. An alternating current resistance ACR is shown in series with the inductance. This alternating current resistance ACR is dependent on the frequency of a signal that is applied to the inductive component. The direct current resistance DCR, in other words the ohmic resistance of the inductive component, which is determined, among other things, by the material used for the coils and their cross-section and their wire length, is also drawn in series with the inductance in the right branch.

In the left branch of the equivalent circuit diagram of Fig. 11 a capacity C is shown. This capacitance C maps the stray capacitance of the inductive component. This stray capacitance is mainly formed between two coils of the inductive component. In the component according to the invention, the plastic component 36 is inserted between the two coils, see Fig. 1 . The stray capacitance C of the inductive component according to the invention can thereby be influenced via the dielectric constant ε _{r of the plastic component 36.}

This in Fig. 11 The equivalent circuit shown also represents a resonance circuit. By selecting the material for the plastic component 36, in other words by choosing the dielectric constant of the plastic of the plastic component 36, the size of the stray capacitance C and thus also the resonance frequency of the inductive component according to the invention can be set . In this way, however, the working range of the inductive component according to the invention can also be changed flexibly.

Claims (16)

1. Core (12) for an inductive element (10) with at least a first side part (18), a middle part (22) and a second side part (20), wherein the middle part (22) has a central portion (30), a first edge portion (32) arranged parallel to the central portion (30), and a second edge portion (34) arranged parallel to the central portion (30), wherein the central portion (30) is arranged between the first and second edge portions (32, 34), and the two edge portions (32, 34) each connect edge portions (26, 28) of the two side parts (18, 20) and continue their shape, wherein at least one plastic component (36) is provided which is provided at least between the central portion (30) and the first edge portion (32) and/or at least between the central portion (30) and the second edge portion (34), in order to adjust a stray capacitance of the inductive element (10) by suitable selection of the dielectric constant ε_r of the plastic used for the plastic component (36) and to influence a secondary magnetic flux of the inductive element by suitable selection of a low relative permeability µ_r of the plastic used for the plastic component (36).
2. Core according to claim 1, characterized in that a dielectric constant of the plastic component (36) lies in the range from 1 to 50, in particular in the range 1 to 10.
3. Core according to at least one of the preceding claims, characterized in that the plastic component (36) is formed from a plastic with low magnetic permeability.
4. Core according to at least one of the preceding claims, characterized in that the plastic component (36) is made from silicone, polyamide, isoprene or latex.
5. Core according to any one of the preceding claims, characterized in that the plastic contains an admixture of carbon, glass granulate, a ceramic compound and/or viscose.
6. Core according to any one of the preceding claims, characterized in that the plastic component (36) fixes the central portion (30), the first edge portion (32) and the second edge portion (34) in a defined position relative to each other.
7. Core according to any one of the preceding claims, characterized in that the plastic component (36) surrounds the central portion (30) of the middle part (22) at least over part of the length of the central portion (30).
8. Core according to any one of the preceding claims, characterized in that the plastic component (36) is formed as a plate-like web (38) arranged perpendicularly to the central portion (30) of the middle part (22), the first edge portion (32) and the second edge portion (34), and comprises three passage openings (42, 44, 46) for receiving the central portion (30) of the middle part (22), the first edge portion (32) and the second edge portion (34).
9. Core according to claim 8, characterized in that a first one of the three passage openings (42, 44, 46) is adapted to the cross-section of the central portion (30) of the middle part (22), a second one of the three passage openings (42, 44, 46) is adapted to the cross-section of the first edge portion (32), and a third one of the three passage openings (42, 44, 46) is adapted to the cross-section of the second edge portion (34).
10. Core according to claim 9, characterized in that the central portion (30) of the middle part (22), the first edge portion (32) and/or the second edge portion (34) are fixed by clamping in the respective passage opening (42, 44, 46).
11. Core according to any one of the preceding claims, characterized in that the first side part (16) and the second side part (20) generally have a cross-section of similar form to the letter E.
12. Core according to claim 11, characterized in that the first side part and the second side part are formed as an E core, PQ core, ETD core or RM core.
13. Core according to at least one of the preceding claims, characterized in that the plastic component (36) has a base plate (40) from which a plate-like web (38) protrudes perpendicularly, wherein the base plate (40) is provided for fixing the first side part (18) and the second side part (20) of the core (12).
14. Core according to claim 13, characterized in that the base plate (40) is provided with fixing means, in particular latching means or clamping means, on its side facing away from the plate-like web (38).
15. Inductive component (10) with a core (12) according to at least one of the preceding claims and at least one coil (14, 16) which at least partially surrounds the central portion (30) of the middle part (22).
16. Inductive component (10) according to claim 15, characterized in that a dielectric constant of the plastic of the plastic component (36) is matched to an inductance of the coil (14, 16) in order to obtain a defined resonant frequency of the inductive component (10).

Images