EP2947667B1 - Interference suppression choke and method for the preparation of an interference suppression choke - Google Patents

Description

The invention relates to a suppression choke for surface mounting on a printed circuit board, wherein the suppression choke comprises holding means with a holding section for fixing a connecting wire. Furthermore, the invention relates to a method for producing a suppression choke. From the DE 298 04 135 U1 is known a rod core choke with a cylindrical core, wherein on the core a winding is applied, which has a substantially cylindrical surface and wherein in the region of the winding on the throttle an elastic clip of a magnetic fields neutral plastic is placed with high thermal stability , which has a substantially U-shaped cross-section and is clamped on the throttle, wherein at least the center leg of the U on its outer side has a flat surface for attacking the vacuum pipette of a placement machine.

The EP 1 916 676 A1 discloses a filter device in which the connection wires of the coil are connected to separately formed lines which are used for the electrical contacting of the filter device. For this purpose, the connecting wires of the coil are each supported on connecting wires of capacitors, which in turn are connected to the respective lines.

From the DE 31 46 168 A1 An inductive component is known in which a wire coil is accommodated in a coil housing formed from two U-shaped housing halves. The position of the coil ends is determined by Drahtausführungsnuten in the housing halves.

The DE 10 2004 048 030 A1 discloses an electrical choke coil in which the leads are configured for a circuit board plug-in assembly and in which the coil body is surrounded by an insulating layer and a holding element. From the US 2009/0195341 A1 It is known to set the connecting wires of a coil in terminal lugs, wherein the connecting wires protrude parallel to the winding axis of the coil. In the publication JP 07 220930 discloses a coil which bears in each case with frontal surfaces on a housing, wherein connection wires of the coil are arranged in a common connection plane.

The US 2005/0122195 A1 discloses a coil which is applied to a bobbin and in which the leads are fixed in electrically conductive connection elements. From the DE 199 17 580 A1 a coil for SMD mounting technology is known, in which on an upper side of the coil and on an underside of the coil each mass points, in particular of a thermosetting plastic, are provided, with which a determination of the coil on the circuit board and a suction of the coil with the help a vacuum suction device can be guaranteed.

The DE 10 2005 022 927 A1 discloses a coil which is arranged on a coil core and provided in regions with a mounted in the plastic injection molding holding element is, which serves to fix the coil on the spool core and optionally for suction by means of a suction device.

From the DE 298 24 118 U1 For example, an SMD mounting inductor is known in which a fine coil wire is wound one or more times around projections of a bobbin to thereby form a pad for a printed circuit board.

US Pat. No. 7,605,131 B2 discloses a filter for SMD mounting with two coils arranged in a housing. The housing forms two U-shaped troughs for receiving the coils and openings for receiving the coil ends.

JP 2007 088363 A discloses an air-core coil for SMD mounting on a printed circuit board. The leads take an acute angle with the circuit board.

The object of the invention is to provide a suppression choke and a method for producing a suppression choke which ensure improved processability of the suppression choke in an automatic processing process (pick-and-place processing).

This object is achieved according to a first aspect of the invention for a suppression choke of the type mentioned above with the features of claim 1.

By the U-shaped configuration of the holding portion, a reliable fixing of the holding means on the wire bobbin body can be achieved. Preferably, a recess in the interior of the at least substantially U-shaped holding portion is adapted to the preferably cylindrically designed outer geometry of the wire bobbin and may include the wire bobbin at least partially positively. Accordingly, the form-fitting reception of the wire bobbin is ensured by the U-shaped holding portion.

By fixing the connection wire to the holding section the holding means, which in turn is coupled to the wire coil, will provide a favorable and robust orientation of the Connection wire with respect to the holding means and the wire bobbin reached. As a result, during processing of the suppression choke in an automatic assembly process (pick-and-place method) it is ensured that the connection wire is located in a predeterminable orientation relative to the holding means on which a gripper, in particular a suction gripper, of the placement machine engages. Accordingly, the suppression choke according to the invention can advantageously be placed on a printed circuit board, which is also referred to as a printed circuit or board.

According to the invention, the suppression choke is designed as a so-called SMD component (surface-mounted device), in which a fixing and electrical contacting, in particular exclusively, is provided on the circuit board surface. For example, an attachment of the suppression choke on contact surfaces of the printed circuit board with a solder paste applied before mounting the suppression choke, which is heated so far after mounting the suppression choke, in particular in a reflow soldering, that form a solid and electrically conductive connection between the Contact surfaces and the connecting wires forms. For this purpose, it is necessary for the connecting wires to rest in each case at least almost flat on a planar, electrically conductive section of the printed circuit board, so that the desired soldering connection with the contact surface is produced during the subsequent soldering process. The flat support of the connecting wire on the connecting surface of the printed circuit board is ensured according to the invention by means of the holding section, which is designed for a predeterminable positioning of the respective connecting wire.

Advantageous developments of the invention are the subject of the dependent claims.

It is expedient if the holding means in each case has a holding section at mutually opposite end regions, wherein each of the holding sections is designed to fix the respective connecting wire. This ensures that both connecting wires of the wire coil, which must be electrically connected to the contact surfaces of the printed circuit board, are received in a predetermined orientation with respect to the holding means and the wire bobbin on the respective holding portions. Preferably, the two connecting wires are arranged in a common plane, which in turn is aligned parallel to the winding axis.

In an advantageous development of the invention it is provided that the holding means on an outer surface has a, preferably flat, gripping surface, which is designed for temporary coupling of a gripping means. Typically, the gripping means is a suction gripper, which presupposes the presence of a flat gripping surface for proper function. Alternatively, the gripping means may also be designed as a finger gripper, for example if several heavy components can be mounted on the printed circuit board, to which the suppression choke can also be counted. In this case, it is not necessary that the gripping surface is flat, but rather a suitable adaptation of the geometry of the gripping surface to the requirements of the finger gripper can be made.

In a further embodiment of the invention it is provided that the holding means comprises a plate-shaped base body, whose longest edge extends along the winding axis and that the holding portions protrude transversely to the longest edge of the base body. By the plate-shaped, in particular cuboidal configuration of the base body is achieved that the wire coil from the holding means away from the holding portions is only affected, so that a heat emission from the suppression choke in an environment is affected as little as possible. In an advantageous development of the holding means, provision may be made for reinforcing webs each protruding at right angles from the plate-shaped base body between the holding sections along the longest edges, but which have a small height relative to the coil diameter of the wire coil and thus do not impair heat radiation of the interference suppression choke. nevertheless ensure stabilization of the plate-shaped body.

Preferably, the holding portion has a recess for a positive reception of the connecting wire. As a result, a reliable fixing of the connecting wire is ensured on the holding section. A use of other materials, in particular an adhesive, is not required. Preferably, the recess in the holding section is adapted to a cross section of the connecting wire such that it tapers again in the direction of an end face of the holding section, so that the connecting wire is received in the holding section in a form-fitting manner after overcoming the taper. A cross section of the recess may preferably be formed according to the cross section of the connecting wire, but this is not a necessary condition for the desired positive reception of the connecting wire in the holding section.

In an advantageous embodiment of the invention, a coil core is accommodated in a coil space limited by the coil bobbin and the holding means forms a stop for an axial fixing of the bobbin along the winding axis. The coil core serves to improve the magnetic efficiency of the suppression choke and is usually made of a ferrite material. Preferably, the length of the bobbin along the Winding axis at least almost completely the length of the wire coil along the winding axis. In order to avoid falling out of the spool core from the wire bobbin, a stop for an axial fixing of the bobbin is provided according to the invention on the holding means. Preferably, two oppositely disposed U-legs of the U-shaped holding means may be connected to a wall portion which forms the required stop for the ferrite core.

In a further embodiment of the invention, it is provided that the connecting wires are arranged in a common, aligned parallel to the winding axis connecting plane and that recesses are formed in the holding portions on end faces of the holding portions, which are aligned opposite to the gripping surface. Thus, the suppression choke for surface mounting (SMD - Surface Mounted Device) is configured on a circuit board, wherein the lead wires lie through the positive fixing in the holding portions in a common connection plane that is consistent with the typically flat surface of the circuit board, to which Suppression choke should be placed. For an advantageous mounting of the wire bobbin in the holding means, the recesses in the holding portions are provided on the front side on the holding portions, so that the coil can be mounted in a mounting direction transverse to its winding axis in the holding means.

It is preferably provided that at least one holding means has a connection tongue projecting beyond the connection plane, which is designed for engagement or a form-locking fixing of the holding means in a printed circuit board bore. With the help of the connection tongue can optionally be a correct positioning of the suppression choke against the contact surfaces on the circuit board and / or a positive locking of the holding means are ensured on the circuit board. For the positive fixing of the holding means is preferably provided that the connection tongue is provided with a barb, which engages behind a rear side of the circuit board and thus ensures a reliable determination of the suppression choke on the circuit board.

The object of the invention is achieved according to a second aspect by a method for producing a suppression choke, wherein the suppression choke is designed for surface mounting on a printed circuit board and a wire bobbin with end protruding leads and a holding means comprising at least one holding portion for receiving a lead wire and wherein the steps: positionally correct positioning of the wire bobbin relative to the holding means and positive insertion of at least one lead wire are provided in a holding portion, wherein the wire coil is wound such that the two lead wires each take an acute angle with a connection level before receiving in the holding means. With this procedure, the required for finishing alignment of the leads against the wire bobbin and the holding means during the press-fitting process for the wire bobbin in the holding means can be ensured.

In an advantageous development of the method, it is provided that the connecting wire is pressed into a recess in the holding section in a form-fitting manner.

Figur 1

eine schematische Darstellung einer Entstördrossel in einer Ansicht von unten, wobei die Entstördrossel eine Drahtspule und ein Haltemittel umfasst,

Figur 2

eine Seitenansicht der Entstördrossel gemäß der Figur 1,

Figur 3

eine Vorderansicht der Entstördrossel gemäß der Figur 1,

Figur 4

eine schematische Darstellung der Drahtspule vor der Montage in das Haltemittel,

Figur 5

eine Ansicht von unten auf das Haltemittel der in den Figuren 1 bis 3 dargestellten Entstördrossel,

Figur 6

eine Schnittdarstellung des Haltemittels,

Figur 7

eine Vorderansicht des Haltemittels,

Figur 8

eine zweite Ausführungsform eines Haltemittels mit stirnseitigen Anschlägen für den Spulenkern,

Figur 9

eine Schnittdarstellung des Haltemittels gemäß der Figur 7 und

Figur 10

eine Vorderansicht einer weiteren Ausführungsform eines Haltemittels, das für eine formschlüssige Aufnahme der Anschlussdrähte ausgebildet ist.

An advantageous embodiment of the invention is shown in the drawing. Hereby shows:

FIG. 1

1 is a schematic representation of a suppression choke in a view from below, wherein the suppression choke comprises a wire coil and a holding means,

FIG. 2

3 a side view of the suppression choke according to FIG. 1,

FIG. 3

4 is a front view of the suppression choke according to FIG. 1,

FIG. 4

a schematic representation of the wire coil before mounting in the holding means,

FIG. 5

a view from below of the holding means in the FIGS. 1 to 3 illustrated suppression choke,

FIG. 6

a sectional view of the holding means,

FIG. 7

a front view of the holding means,

FIG. 8

a second embodiment of a holding means with end stops for the bobbin,

FIG. 9

a sectional view of the holding means according to the FIG. 7 and

FIG. 10

a front view of another embodiment of a holding means, which is designed for a positive reception of the connecting wires.

One in the FIGS. 1 to 3 shown suppression choke 1 is exemplified as an SMD component for surface mounting (SMD - Surface Mounted Device) on a printed circuit or printed circuit board of an electrical or electronic circuit, not shown. Such suppression chokes 1 are used for example for suppression of electric motors or for shielding electrical circuits against external interference.

The suppression choke 1 comprises by way of example a wire coil 2 and a holding means 3 coupled to the wire coil 2. In this case, the wire coil 2 is designed as an example with a circular cross section, so that a substantially cylindrical outer contour results for the wire coil 2. The wire coil 2 can be thoughtfully divided into a helical wire bobbin 4 and two respectively projecting from the wire bobbin 4 connecting wires 5. A production of such a wire bobbin 4, for example, by winding a preferably provided with an insulating layer, in particular a coating, spool wire to a, not shown, preferably cylindrical winding core, are prepared. By way of example, it is provided that successive turns of the wire bobbin 4 are arranged in direct contact with previous and subsequent turns, resulting in a particularly compact design for the wire bobbin 4. The connecting wires 5 are each made in one piece with the wire bobbin 5.

In one embodiment, not shown, a pitch for the individual turns of the wire bobbin greater than the diameter of the coil wire may be selected so that there is an air gap between adjacent turns.

The turns of the wire bobbin 4 determine a winding axis 6, which corresponds to an extension axis of the winding core, not shown. The terminal wires 5 arranged on the end of the wire bobbin 4 are aligned tangentially to the turns of the wire bobbin 4 for the planned use of the suppression choke 1 as an SMD component, and are embodied in an exemplary linear fashion. By way of example, the connecting wires 5 each extend in mutually opposite spatial directions, but are transverse to the winding axis 6 aligned and preferably arranged in a common connection level 7. The connection level 7 is synonymous with a preferably flat surface of a printed circuit board or printed circuit, not shown, on which the suppression choke 1 is to be placed. In order to ensure advantageous processability and a reliable fixing, in particular a cohesive fixing in the course of a soldering process, for the suppression choke 1 on the printed circuit board, it is necessary for the connecting wires 5 to be flat or aligned relative to the connecting plane 7. Otherwise, an insufficient contact between the lead wires 5 and the printed circuit contact surfaces, not shown, is formed, so that in the proposed soldering possibly no electrical connection between the contact surfaces of the printed circuit board and the lead wires is made or the suppression choke is unilaterally lifted off the circuit board, which would lead to a malfunction of the circuit board.

In order to ensure the desired orientation of the connecting wires 5 for mounting the suppression choke 1 on the printed circuit board, not shown, the holding means 3 is provided, which is made by injection molding, preferably made of a heat-resistant plastic. That in the FIGS. 1 to 3 shown holding means 3 includes two exemplified at opposite end portions holding portions 8, which are provided on the one hand for fixing the holding means 3 to the wire coil 2 and on the other hand serve for the correct alignment of the connecting wires 5. Between the holding portions 8, the holding means 3 comprises a plate-shaped base body 9, as shown in particular from the partially sectioned view of FIG. 2 and the sectional view of the FIG. 5 can be seen. By way of example, a longest edge 10 of the main body 9 extends parallel to the winding axis 6 of the wire spool 2. It can also be provided that reinforcing webs 15, which are aligned transversely to the largest surfaces 10 and 11, are provided on lateral end regions of the main body 9, which are shown as an example between the holding sections 8 extend and serve to increase the flexural strength of the body 9.

The holding sections 8 extend along the winding axis 6 only over a fraction of the length of the holding means 3 and each have a recess 16 which is adapted in its cross-section to a cross section of the wire bobbin 4 in order to accommodate the wire bobbin 4, preferably positively , Preferably, the geometric configuration for the holding portions 8 of the holding means 3 is such that the wire spool 2 can elastically deform the respective holding portion 8 during a press-fit operation to effect a positive reception in the recess 16.

By way of example, the recess 16 is designed in the form of a circle section, wherein in combination with a cuboidal outer envelope for the holding means 3 in a frontal view according to the Figures 2 and 5 a substantially U-shaped cross-section for the holding sections 8 results. In this case, the holding portion has a first U-leg 17 and a second U-leg 18, which are connected to each other by means of a connecting web 19, which is formed substantially by the base body 9. At the free end portions of the U-legs 17 and 18 are exemplary chamfers 20, 21 are formed, which support a sliding in of the wire bobbin 4 during the press-fitting process in the holding portions 8 of the holding means 3.

In the in the FIGS. 1 to 3 illustrated embodiments of the holding means 3, the determination and alignment of the leads 5 is achieved in that the wire coil 2 is wound such that the two leads 5 relative to the connection level 7 before receiving in the holding means 3 each have an acute angle 27 with the connection level. 7 take, as in the FIG. 4 is shown. In this case, the so-called "overwinding" of the wire coil 2 is selected so that the connecting wires 5 are aligned in the desired manner parallel to each other and to the connection level 7 after mounting the wire coil 2 in the holding means 3 by the resulting force relationships. Furthermore, it should be noted that the "overwinding" is chosen so that the bias voltage in the wire bobbin 4 is so small that the wire spool 2 is not pushed out of the holding means 3 again. As a result of the "overwinding" of the wire coil 2, a reliable contact of the connecting wires 5 at end faces 22, 23 of the holding sections 8 is ensured. It is advantageous if in the end faces 22, 23 of the holding portions 8 each recesses 24, 25 are provided for receiving the connecting wires 5, so that the connecting wires 5 are guided and fixed in an advantageous manner.

Alternatively, it can be provided that the connecting wires lie without a recess on a, in particular flat, executed end side of the holding sections or that the connecting wires 5 as in the in FIG. 10 embodiment shown are received in a recess 54 of a holding means 53, which is provided for a positive reception of the connecting wires 5, wherein in the latter case, an "overwinding" can be at least almost or completely omitted.

The design of the holding means 3 for the suppression choke 1 according to the FIGS. 1 to 3 goes in particular from the FIGS. 5 to 7 out. In the embodiment of the holding means 3 shown there, the use of an overwound wire spool 2 is provided. The extent of the holding sections 8 along the winding axis 6 can be selected depending on the material of the holding means 3 and the length of the wire spool 2, it merely has to be ensured that a greater holding force is exerted by the positive reception of the wire spool 2 in the holding means 3, as is introduced by the reverse deformation of the recorded in the holding means 3 wire coil 2. This ensures that the connecting wires 5 in a desired manner flat against the end faces 22, 23 of the holding sections 8 and are aligned parallel to each other.

In the in the FIGS. 8 and 9 illustrated second embodiment of a holding means 33, the same reference numerals as for the holding means 3 are used for functionally identical components. In contrast to the holding means 3, a wall section between U-limbs 37, 38 of the holding section 35 is provided in each case at the end on the holding means 33. This wall portion 34 serves as a stop for the male inside the wire coil 2, in the FIG. 2 Accordingly, no additional precautions must be taken to set the spool core 26 in the wire coil 2, whereby a simplification for the installation of the suppression choke 1 can be achieved.

A variant of the embodiment of the holding means 53, which is designed for a positive reception of the respective connecting wire 5, goes out of the FIG. 10 out. The Recess 54 is formed circular-cylindrical, wherein a central axis for the circular cylindrical recess 54 is disposed in the holding portion 55 below the end face 56 of the holding portion 55, so that the respective lead wire 5 can be introduced into the recess 54 only under elastic deformation of the wall of the recess 54, but then there is positively locked.

Claims (10)

1. Suppressor choke for surface mounting on a printed circuit board, having a wire coil (2) which has a helical wire coil body (4) extending along a winding axis (6) and having connecting wires (5) projecting at the respective ends of the wire coil body (4) and projecting transversely to the winding axis (6), and having a holding means (3; 33; 53) coupled to the wire coil (2) and extending along said wire coil body (4), said holding means (3; 33; 53) comprises a holding section (8; 35; 55) which is U-shaped for positively receiving a portion of the wire coil body (4) and which is designed for fixing a connecting wire (5), wherein the wire coil (2) being wound in such a way that the two connecting wires (5) each take up an acute angle (27) with a connecting plane (7) before being received in the holding means (3).
2. Suppressor choke according to claim 1, characterized in that the holding means (3; 33; 53) having a respective holding portion (8; 35; 55) at opposite end portions, each of the holding portions (8; 35; 55) being adapted for fixing the respective connecting wire (5).
3. Suppressor choke according to claim 1 or 2, characterized in that the holding means (3; 33; 53) has, on an outer surface (11), a preferably planar, gripping surface which is designed for the temporary coupling of a gripping means.
4. Suppressor choke according to claim 1, 2 or 3, characterized in that the holding means (3; 33; 53) comprises a plate-shaped base body (9) whose longest edge (10) extends along the winding axis (6) and that the holding portion (8; 35) or the holding portions (8; 35) project transversely to the longest edge (10) of the base body (9).
5. Suppressor choke according to one of the preceding claims, characterized in that the holding section (55) or the holding sections (55) having a recess (54) for positively receiving the connecting wire (5).
6. Suppressor choke according to one of the preceding claims, characterized in that a coil core (26) is accommodated in a coil space which is bounded by the wire coil body (4) and in that the holding means (33) forms a stop (34) for axial fixing of the coil core (26) along the winding axis (6).
7. Suppressor choke according to claim 3, characterized in that the connecting wires (5) are arranged in a common connecting plane (7) aligned parallel to the winding axis (6) and in that recesses (24, 25; 54) are provided in the holding section (8); 35; 55) or in the holding sections (8; 35; 55) and are formed on end faces (22, 23) of the holding section (8; 35; 55) or of the holding sections (8; 35; 55) which are aligned opposite to the gripping surface (11).
8. Suppressor choke according to claim 7, characterized in that at the holding means has a connection tongue which projects beyond the connection plane and is designed for engagement or positive locking of the holding means in a printed circuit board bore.
9. Method for producing a suppressor choke which is designed for surface mounting on a printed circuit board and which comprises a wire coil body (4) with connecting wires (5) projecting at the ends and a holding means (3; 33; 53) with at least one U-shaped holding section (8; 35; 55) for receiving a connecting wire (5), comprising the steps: positioning the wire coil body (4) in the correct position with respect to the holding means (3; 33; 53), positively pressing the wire coil body (4) into the holding portion (8; 35; 55), the wire coil (2) being wound in such a way that the two connecting wires (5) each assume an acute angle (27) with a connecting plane (7) before being received into the holding means (3).
10. Method according to claim 9, characterized in that the connecting wire (5) is pressed into a recess (24, 25; 54) in the holding section (8; 35; 55) in a positive-locking manner.

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