HK1200974B - Inductive component - Google Patents

Description

Induction element

Technical Field

The invention relates to an inductive element comprising a coil having a coil winding and a coil core, and further comprising a housing forming an outer shell of the coil and having a housing lower part.

Background

Inductive elements of this type are known. Here, it is important for the properties of the inductive element that the air gap between the coil core and the outer shell is observed in a precise manner.

With the known inductive element, the coil core with the flange at each of its two ends and the housing are arranged in an outer plastic shell with positioning means for both the coil core and for the housing. Thus, an accurate positioning between the two parts of the coil can be produced and an air gap is ensured to be observed (DE 102007063170 a 1).

Disclosure of Invention

The object of the present invention is to create an inductive element that is particularly suitable for automated mounting.

To achieve this object, the invention proposes an inductive element having the features specified in claim 1. The improvement of the invention is disclosed by the attached technical scheme.

The inductive element thus contains a holder for the coil core within the housing. The holder is formed such that the coil core is held without displacement at least in its own longitudinal direction. Therefore, it is ensured that the gap between the end surface of the coil core and the adjacent portion of the inner face of the housing is kept constant.

A holder arranged within the housing forming the casing makes an outer housing superfluous for positioning only.

In a refinement of the invention, the holder can have, for each end of the coil core, a bearing block with a bearing support for the respective end region of the coil core. The engagement at the end regions of the coil core is advantageous, since the middle region of the coil core then remains free for the windings of the coil.

In another embodiment of the invention, the bearing support of the bearing block has an upwardly open cavity. This cavity preferably has a curvature corresponding to the diameter of the coil core. The coil core is thus arranged in this cavity so as to also prevent displacements transverse to the longitudinal axis.

According to another feature of the invention, the bearing block may have, at the end arranged closer to the inner face of the wall of the housing, a transverse rib which runs parallel to the wall of the housing and is therefore perpendicular to the end surface of the coil core and against which this end surface rests when the coil core is inserted into its holder. Here, the transverse rib only needs to engage a portion of the end surface, since this is entirely sufficient for axial fixing. A large part of the end surface of the coil core may thus remain free, so that a true air gap is formed between the end surface and the housing.

This can also be achieved by a transverse rib of suitable size if for certain reasons it is desired not to provide an air gap but to fill it with material of the transverse rib.

In a further refinement of the invention, the bearing support can be conical. A conical shape may be used to concentrate the coil core. In particular, the conical shape of the bearing support may correspond to a bevel provided at the end of the coil core.

In another embodiment of the invention, the outer face of the bearing block may bear in a planar manner against the inner face of the housing.

The thickness of the transverse rib measured in the axial direction of the coil core may correspond to the dimension of the air gap.

In a refinement, the invention proposes that the housing is assembled from the hood-shaped upper part and the base. Here, in particular, the upper portion may have a cubic shape.

According to the invention, the holder for the coil core may be arranged on the base, in particular integrally formed on the base. The assembly of the inductive element can thus be particularly simple, since the coil with the core is first inserted into the holder of the base of the housing, after which the upper part is then fitted onto and connected to said base.

According to the invention, the housing upper part can consist of magnetically conducting material, wherein the housing upper part is preferably formed as one piece.

The base, which can also be used for attaching the holder for the coil core, is preferably composed of a non-conductive material, in particular plastic.

The housing and thus the inductive element will be fastened using SMD technology. Contact elements arranged on the outside on the housing base of the housing are connected to or formed integrally with electrodes arranged inside the housing. The ends of the coil windings are attached (in particular, welded) to electrodes inside the housing.

It has proven to be advantageous to arrange the electrodes parallel to the wall of the housing, wherein in particular they have a flat contact surface for the end region of the coil winding. Here, the connection to the lateral surface of the end of the wire winding is preferably made. A large connecting surface is thus available which can also resist large forces and thus provide a stable connection between the coil winding and the contact surface on the outside of the inductive element.

For a particularly simple and advantageous installation, the base of the housing can have a rectangular shape, wherein the corners of the rectangle are chamfered. Thus, the housing upper part may have a protrusion on its end edge at the corner that is complementary to the chamfered corner of the base part. In the assembled condition, the end edge of the upper part can then lie in the same plane as the outer face of the base part.

In a further refinement of the invention, the base can have on its upper face facing the interior of the housing in the region of the chamfered corner an outwardly descending inclined surface with which an equally inclined surface formed on the inner face of the projection of the upper part of the housing cooperates. The two parts forming the housing are thus in fact self-aligning and centered when the housing is assembled.

The invention also proposes a method for mounting an inductive element as already described herein. Here, the coil is first wound as an air-core coil and its ends are provided with solder. Next, the coil is slid onto or into the coil core. Next, the coil is placed onto the bearing block with the end surfaces of the coil core abutting the transverse ribs. Then, the wire ends of the coil windings are welded to the upwardly protruding electrodes.

Next, glue is injected into the housing upper part and the housing upper part is connected to the housing base. Once the glue is cured, the sensing element is completed.

Drawings

Further features, details and advantages of the invention will emerge from the claims and the abstract, from the following description of a preferred embodiment of the invention and with reference to the drawings, in which the wording of the claims and the abstract is incorporated by reference into the content of the description, in which:

FIG. 1 shows a perspective view from below of a completed inductive element according to the present invention;

FIG. 2 shows a perspective plan view of the housing base;

FIG. 3 shows a perspective view of the upper portion of the housing diagonally from below;

FIG. 4 shows a longitudinal cross-section through the base of the housing;

FIG. 5 shows a longitudinal cross section through a housing base with an inserted coil core;

FIG. 6 shows a perspective view of the arrangement in FIG. 5;

fig. 7 shows an illustration corresponding to fig. 6 of a modified arrangement of coils in the housing base.

Detailed Description

Fig. 1 shows a perspective view from below of an inductive element according to the invention. The inductive element has a housing with a hood-shaped upper part 1, which has approximately a cuboid shape. The cube is completely closed except for the lower face. A housing base 2 closing the open end face of the upper part 1 also belongs to the housing. On the lower face of the housing base 2, two soldering pads 3 are visible, by means of which the inductive element is fastened to the printed circuit board using SMD technology. The corners of the base 2 are chamfered so that edges 4 continuing in an inclined manner are formed there. These side edges 4 of the base, which run at a slope, correspond to projections 5 on the end face of the upper part 1 of the housing. The lower face of the projection 5 is thus in the same plane as the lower face of the base 2. In the region of several sides of the base 2, the end edge of the housing upper part 1 rests on the upper face of the housing base 2.

The open side of the housing upper part 1 is also clearly visible from fig. 3 to which reference will now be made. Here, it can be seen in particular that the projection 5 at the corner of the open side of the housing upper part 1 actually projects relative to the end edge 6 of the housing upper part 1. The end edges 6 are located between the projections 5 in one plane. In the assembled state, the end edges 6 are located between projections on the upper face of the housing base 2. The inwardly directed side surfaces 7 of the projections 5 run at a slope in planes converging in the direction of the closing side opposite the open side of the housing upper part 1.

Fig. 2 now shows a perspective plan view of the housing base 2. The already mentioned inclined surface 4 can also be seen here. As can be seen from fig. 2, the upper face 8 of the housing base 2, which is flat in itself in the region of the chamfered corner, has an inclined surface 9 which descends outwards at a gradient. These inclined surfaces 9 correspond in their configuration and size to the inclined surfaces 7 on the inner face of the projections 5 of the housing upper part 1.

Two bearing blocks 10 are integrally formed on the upper face 8 of the housing base 2 and have the form of a cube-shaped cylinder with parallel side walls. The upper face of the bearing block 10 forms a cavity 11 which is delimited in each case by a rib 13 in the direction facing away from one another the outer surfaces 12. The inner face of the rib 13 is flat and continues parallel to the outer face 12 of each bearing block 10, which is also flat.

As can also be derived from the perspective illustration in fig. 2, the cavity 11 continues in an inwardly descending manner on the upper face of the bearing block 10.

The soldering pads 3 mentioned with reference to fig. 1 continue on the upper side 8 of the housing base 2 into the electrode 14, which has a limb 14a resting on the upper side. In the outer region, the electrodes are bent upwards and form a contact surface 15 which is flat and continues perpendicular to the upper face 8 of the housing base 2.

In the illustrated example, the upwardly directed extension of the contact surface 15 of the electrode 14 (i.e. away from the upper face 8 of the housing base 2) reaches almost as far as the cavity 11 and can also be formed to be longer. This surface 15 can be used for contacting the ends of the coil windings.

A longitudinal section through the housing base 2 is illustrated in fig. 4. Here, a mirror-image arrangement of the two bearing blocks 10 can be seen in particular. The outer surface 12 thereof runs perpendicularly to the lower surface of the housing base 2. The inner faces 16 also run perpendicular to the housing base 2 and are therefore parallel to one another. The two bearing blocks 10 have equal height.

The slope of the cavity 11 corresponds approximately to the slope 17 at the end of the coil core 18 belonging to the coil arranged in the inductive element according to the invention.

Fig. 4 shows a longitudinal section through the housing base 2, while fig. 5 shows the same longitudinal section, however with the coil now inserted in the housing base 2. The coil contains a cylindrical coil core 18, said coil core 18 having two flat end surfaces 19 which run perpendicular to the longitudinal axis of the coil core 18 and are thus parallel to one another. The coil core 18 is surrounded by coil windings 20. The coil winding 20 leaves both ends of the coil core 18 free so that the coil core 18 can be inserted into both bearing blocks 10. The ramp 17 rests in the cavity 11 and the end surface 19 abuts against the inner face of the rib 13. Since the curvature of the cavity 11 is adapted to the diameter of the coil core 18, the coil is fixed both in the direction of its own axis and in the direction perpendicular to the drawing plane of fig. 5. Once the housing upper part 1 has been slid onto the housing base 2, a defined constant air gap is thus present between the two end faces 19 and the adjacent region of the wall of the housing upper part 1.

The wire ends 21 of the coil windings 20 are led down in a straight line at the ends of the coil windings and are welded to the contact surfaces 15 of the electrodes 14. This is indicated in fig. 5 at the wire end 21 arranged behind the drawing plane.

Fig. 6 now shows a perspective view of the arrangement of the coil on the housing base 2. The leading wire end 22 of the coil winding 20 is led down as far as the electrode 14 and soldered to the contact surface 15. Thus, a connection between the wire 22, which is cylindrical in the end region, and the contact surface 15 is formed on a lateral surface of the wire of the coil winding 20. By applying a holding force by the electrode holder, the lead end deforms elliptically. A tolerance gap is provided between the front lead end 22 and the branch 14a of the electrode 14 resting on the upper face of the housing base 2. It can also be deduced from fig. 6 that the contact surface can be increased by extending the electrodes in a direction perpendicular to the housing base 2.

Fig. 7 shows such a possibility, wherein the upwardly directed part of the electrode is directed further upwardly together with the contact surface 15 formed on its inner face. In addition, it is supported outwardly by a corresponding corner support 23 integrally formed with the bearing block 10. In this case, the wire ends 22, 21 may be guided upward.

The coil is thus also fixed in three dimensions by soldering the lead ends 21, 22 to the contact surface 15 of the electrode 14.

Once the wire ends 22 have been connected to the contact surface 15, the previously provided housing upper part 1, which has glue at least on its end surface 6, is fixed to the housing base 2. The inner face of the wall of the upper part 1 of the housing rests on the outer face 12 of the bearing block 10. Thus defining a gap thickness corresponding to the thickness of the rib 13.

Due to the large contact surface between the contact surface 15 of the electrode 14 and the lead ends 21, 22 of the coil winding 20, a sufficiently large pull-out force is achieved, so that the inductive element forms a stable unit.

Claims (10)

1. An inductive element, comprising

A coil core (18) having a coil winding (20) and two end surfaces (19),

a housing, which surrounds the coil,

a holder for the coil core (18), the holder being arranged in the housing,

and the coil core (18) is held in the holder without displacement in the longitudinal direction, and further comprises

A distance forming a gap between the end surface (19) of the coil core (18) and an inner face of the housing in a region opposite the end surface (19) of the coil core (18), wherein

For each end of the coil core (18), the holder has a bearing block (10), the bearing block (10) having a bearing support for the respective end region of the coil core (18),

the bearing support has an upwardly open cavity (11), the cavity (11) having a curvature corresponding to the diameter of the coil core (18),

the bearing block (10) has ribs (13) which define the bearing support and engage the end surface (19) of the coil core (18), and

the bearing support is conical.

2. Inductive element according to claim 1, wherein an outer face (12) of the bearing block (10) bears in a planar manner against the inner face of the housing.

3. Inductive element according to claim 1 or 2, wherein the housing has a hood-shaped upper part (1) with a housing base (2).

4. The inductive element according to claim 3, wherein the holder is arranged on the housing base (2), in particular integrally formed on the housing base (2).

5. The inductive element according to claim 3, wherein the housing upper part (1) optionally consists of a magnetically conducting material and the housing base (2) optionally consists of a non-conducting material.

6. Inductive element according to claim 1 or 2, comprising electrodes (14) arranged on the inner face of the housing for connection to ends (21, 22) of the coil winding (20).

7. Inductive element according to claim 6, wherein the electrode runs parallel to the wall of the housing and has a flat contact surface (15) for the end regions of the coil winding, wherein the ends (21, 22) of the coil winding (20) are welded to the electrode, preferably via their lateral surfaces.

8. Inductive element according to claim 3, wherein the housing base (2) has a rectangular shape with chamfered corners and the housing upper part (1) has on its end edge (6) a projection (5) which is formed in a complementary manner to these chamfered corners.

9. Inductive element according to claim 8, wherein the housing base (2) has on its upper face (8) in the region of the chamfered corner an outwardly descending inclined surface (9), the inclined surface (7) formed on the inner face of the projection (5) of the housing upper part (1) cooperating with the inclined surface (9).

10. Method for mounting an inductive element according to one of the preceding claims, comprising the following method steps:

winding the coil and wetting the wire ends (21, 22) with solder,

sliding the coil onto a coil core (18),

placing the coil core (18) on a bearing block (10),

welding the ends of the coil windings (20) to the electrodes of the housing base (2),

the glue is injected into the upper part (1) of the housing,

connecting the housing base (2) to the upper part (1),

the glue is cured.