Patent Description:
Document <CIT> describes an electromagnetic device comprising an elongated magnetic core surrounded by a coil, the magnetic core and the coil being embedded in a waterproof enclosure. This document does not describe how to maintain the magnetic core centered within the mold during the overmolding thereof.

Document <CIT> also describes a similar electromagnetic device in which the magnetic core and the coil are supported in a bobbin introduced in the mold to center the magnetic core during the overmolding operation, but this solution is labor intensive requiring the fabrication and the placement of said bobbin.

Other documents, such documents <CIT>), <CIT> and other similar documents, describe how to retain an element within a mold using retractile levers integrated in the mold, but this technical solution greatly increases the production and maintenance cost of the mold.

Documents <CIT>, <CIT> and <CIT> disclose an electromagnetic device according to the preamble of claim <NUM>.

The present invention solves those and other problems.

According to a first aspect, the present invention concerns to a waterproof electromagnetic device, as defined in claim <NUM>.

Said electromagnetic device can be, for example, an inductor, an antenna, a near field antenna, an electric transformer, among others.

The proposed waterproof electromagnetic device comprises, in a manner already known in the state of the art, the following features:.

The overmolding, typically using a plastic or a thermoplastic material, creates a surrounding hard shell which seals all the water channels communicating the interior elements with the exterior of the enclosure, preventing the entrance of water therein and also increasing the structural resistance of the waterproof electromagnetic device, for example against impacts.

The present invention further proposes, in a manner not known from the available state of the art, the inclusion of several protrusions projecting from the magnetic core towards an external surface of the enclosure, providing a centering of the magnetic core within the enclosure during the overmoulding operation.

According to that, the magnetic core includes protrusions extending from the magnetic core, extending through the enclosure, each protrusion including a protrusion tip reaching the external surface of the enclosure.

It will be understood that the external surface of the enclosure is the surface determining its envelope, which is defined by the shape of the mold where it has been injected.

Those protrusions extend preferably from at least two opposed sides of the magnetic core in two opposed directions. It is also preferred to include at least three protrusions on the same side of the magnetic core to provide stability when the magnetic core is inserted in the mold before the overmolding, being then the magnetic core supported on the protrusion tips of those at least three protrusions on the same side of the magnetic core.

The magnetic core is preferably an elongated magnetic core which define a longitudinal direction, in which case the protrusions extend preferably in a radial direction regarding this longitudinal direction.

According to an embodiment of the present invention, the electronic circuit board is partially embedded in the magnetic core, providing a support for the electronic circuit board during the overmolding operation, the magnetic core supporting the electronic circuit board away from the surfaces of the enclosure mold during the overmoulding operation.

Preferably the connection pins of the electronic circuit board are connected to electrically exposed ends of electric cables. The connection pins and the electrically exposed ends of the electric cables will be also embedded in the enclosure and the electric cables will extend outside the enclosure. In that manner, the electromagnetic device signals can we communicated through said cables, and the connection between the cables and the coil is waterproof and has an increased resistance.

According to a second aspect described in claim <NUM>, the present invention is also directed towards a production method for producing a waterproof electromagnetic device.

The proposed method comprises, in a manner already known in the state of the art, the following:.

The method also comprises, in a manner not known from the state of the art, the following:
the magnetic core is produced including several protrusions projecting from the magnetic core in radial directions, each protrusion including a protrusion tip which contacts with the enclosure mold when the magnetic core is introduced in the enclosure mold, providing a centering of the magnetic core within the enclosure mold during the overmoulding of the enclosure.

According to that, the magnetic core is produced including protrusions extending from the magnetic core away from said magnetic core, each protrusion defining a protrusion tip on a distal end thereof.

When the magnetic core, and the coil and electric circuit board attached to the magnetic core, are introduced in the enclosure mold, those protrusion tips contact with inner surfaces of the enclosure mold keeping the rest of the magnetic core and the other elements attached thereto away from inner surfaces of the enclosure mold and in a centered position, avoiding its movement during the overmolding operation.

Then, with the enclosure mold closed, the molten material constitutive of the enclosure is injected into the enclosure mold, completely surrounding the elements contained therein except for the protrusion tips, which will be coincident with the external surface of the formed enclosure in those points where the protrusion tips contact with the inner surface of the mold.

To electrically insulate the magnetic core, it is also proposed to optionally cover the protrusion tips with a waterproof and electrically insulating seal, or with a waterproof and electrically insulating seal made of resin, before the insertion of the magnetic core in the enclosure mold or after the extraction of the waterproof electromagnetic device from the mold.

Preferably the magnetic core is an injection molded magnetic core, for example made of composite materials comprising a polymeric matrix with embedded hard magnetic filler particles.

According to an embodiment of the proposed method, to produce the magnetic core a portion of the electronic circuit board is inserted in a core mold, and the magnetic core is produced by molding in said core mold, obtaining a magnetic core with the electronic circuit board attached thereto and partially embedding therein in a position selected to keep the electronic circuit board away from the enclosure mold during the overmolding of the enclosure.

The foregoing and other advantages and features will be more fully understood from the following detailed description of an embodiment with reference to the accompanying drawings, to be taken in an illustrative and non-limitative manner, in which:.

According to the preferred embodiment of the present invention, the proposed waterproof electromagnetic device comprises a magnetic core <NUM> surrounded by at least one coil <NUM> wounded therearound, an electronic circuit board <NUM> including at least connection pins <NUM> electrically connected to the at least one coil <NUM>, and an enclosure <NUM> overmolded on a waterproof manner surrounding the magnetic core <NUM>, the at least one coil <NUM> and the electronic circuit board <NUM>.

Typically, the coil <NUM> will be one coil <NUM> wound around one X axis of the magnetic core <NUM>, or two coils <NUM> wound around two orthogonal axis X and Y of the magnetic core <NUM> or three coils <NUM> wound around three orthogonal axis X, Y and Z of the magnetic core <NUM>.

The proposed magnetic core <NUM> further includes several protrusions <NUM> projecting from the magnetic core <NUM> towards an external surface of the enclosure <NUM>, so that a centering of the magnetic core <NUM> within the enclosure <NUM> is provided during the overmoulding operation.

Preferably the electronic circuit board <NUM> is partially embedded in the magnetic core <NUM>, so that it is attached thereto during the overmolding of the enclosure, the magnetic core <NUM> maintaining the position of the electronic circuit board <NUM> during the overmolding of the enclosure <NUM>.

The connection pins <NUM> of the electronic circuit board <NUM> are preferably connected to electrically exposed ends of electric cables <NUM>. In such case, the connection pins <NUM> and the electrically exposed ends of the electric cables <NUM> will be also embedded in the enclosure <NUM>, a portion of the electric cables <NUM> extending outside the enclosure <NUM>. This feature ensures the proper signal transmission and the waterproofing of the connection between the electric cables <NUM> and the connection pins <NUM>.

According to an embodiment, each electric cable <NUM> includes a sealing portion <NUM> not embedded in the enclosure <NUM>. Said sealing portion <NUM> will be comprised between two portions of the cable embedded in the enclosure <NUM>. Each sealing portion <NUM> will be covered by a waterproof and electrically insulating seal <NUM>, or by a waterproof and electrically insulating seal <NUM> made of resin, providing an additional waterproof sealing.

Preferably, the sealing portion <NUM> of the electric cables <NUM> are placed in a cavity of the enclosure which is filled with the waterproof and electrically insulating seal <NUM>.

An embodiment of this feature can be seen in <FIG>, where the cavity is a blind hole. The inner surfaces of the blind hole define two facing surfaces of the enclosure <NUM>, each cable passing through both facing surfaces defining the sealing portion <NUM> of the cable between said facing surfaces. The insulating seal <NUM> fills the blind hole completely surrounding the sealing portion <NUM>.

According to an alternative embodiment, the cavity can be a through hole of the enclosure <NUM>.

Each protrusion <NUM> defines a protrusion tip <NUM> on its distal end regarding the rest of the magnetic core <NUM>.

According to an embodiment, the external surface of the enclosure <NUM> includes depressed regions defining cavities. Optionally, at least some of the protrusion tips <NUM> of the protrusions <NUM> will reach the external surface of the enclosure <NUM> on the depressed regions of the external surface defining the cavities, so that said protrusion tips <NUM> will be housed within a cavity. In any case, preferably the protrusion tips <NUM> are covered by waterproof and electrically insulating seal <NUM>, or by a waterproof and electrically insulating seal <NUM> made of resin.

When the protrusion tips <NUM> are housed within a cavity of the enclosure, the insulating seal <NUM> may fill said cavity and also may be flush with the external surface of the enclosure surrounding the cavity, providing a flat enclosure <NUM>. This embodiment can be seen in <FIG> (upper side).

According to an alternative embodiment, the protrusion tips <NUM> are flush with the enclosure <NUM>, in which case the insulating seal <NUM> may be applied on top of the enclosure <NUM>, producing a bulge. This embodiment can be seen in <FIG> (lower side). Preferably both upper and lower sides of the enclosure <NUM> have the same configuration.

Optionally, the external surface of the enclosure <NUM> can include a longitudinal groove <NUM> extending along the entire length of the enclosure <NUM> for cable routing.

The present invention also proposed a production method for producing a waterproof electromagnetic device such the electromagnetic device described above.

The proposed method comprises producing a magnetic core <NUM> surrounded by at least one coil <NUM>, the at least one coil <NUM> being connected to connection pins <NUM> of an electronic circuit board <NUM>, inserting the magnetic core <NUM>, the surrounding at least one coil <NUM> and the electronic circuit board <NUM> in an enclosure mold and closing the enclosure mold, and overmoulding within the enclosure mold an enclosure <NUM> on a waterproof manner surrounding the magnetic core <NUM>, the at least one coil <NUM> and the electronic circuit board <NUM>, obtaining the waterproof electromagnetic device. Later, the waterproof electromagnetic device is extracted from the enclosure mold.

The method further proposed to produce the magnetic core <NUM> including several protrusions <NUM> projecting from the magnetic core <NUM> in radial directions, each protrusion <NUM> including a protrusion tip <NUM> which contacts with the inner surfaces of the enclosure mold when the magnetic core <NUM> is introduced in the enclosure mold, providing a centering of the magnetic core <NUM> within the enclosure mold during the overmoulding of the enclosure <NUM>.

Preferably the enclosure mold includes protruding centering configurations complementary with the protrusion tips <NUM> which protrude from the inner surface of the enclosure mold. Those protruding centering configurations determine cavities in the external surface of the enclosure <NUM> once overmolded within the enclosure mold.

In this case, the protrusion tips <NUM> will contact the enclosure mold in the protruding centering configurations when inserted in the enclosure mold so that, after the overmolding, the protrusion tips <NUM> will be coincident with the external surface of the enclosure <NUM> within said cavities.

It is also proposed to cover the protrusion tips <NUM> with a waterproof and electrically insulating seal <NUM>, for example made of resin, either before the insertion of the magnetic core <NUM> in the enclosure mold or after the extraction of the waterproof electromagnetic device from the enclosure mold.

When the protrusion tips are coincident with the external surface of the enclosure in said cavities, the waterproof and electrically insulating seal <NUM> will fill said cavities, obtaining a flush and smooth external surface of the resulting waterproof electromagnetic device.

According to an embodiment, to produce the magnetic core <NUM>, a portion of the electronic circuit board <NUM> is inserted in a core mold, and the magnetic core <NUM> is produced by molding in said core mold. As a result, a magnetic core <NUM> with the electronic circuit board <NUM> attached thereto and partially embedding therein will be obtained. The position of the electronic circuit board <NUM> in regard to the magnetic core <NUM> will be selected to keep the electronic circuit board <NUM> supported by the magnetic core <NUM> away from the inner surfaces of the enclosure mold during the overmolding of the enclosure <NUM>.

Preferably, before the insertion of the magnetic core <NUM> in the enclosure mold, the connection pins <NUM> are connected to electrically exposed ends of electric cables <NUM>, for example by welding. Later, the magnetic core <NUM>, the at least one coil <NUM> and the electronic circuit board <NUM> with the electric cables <NUM> connected thereto will be inserted in the enclosure mold, the electric cables <NUM> extending outside the enclosure mold through cable exit openings provided in the enclosure mold. The overmolding operation will then produce the enclosure <NUM> embedding also the connection pins <NUM>, the electrically exposed end of each electric cable <NUM> and a portion of each electric cable <NUM>, which is contained within the enclosure mold between the connection pins <NUM> and the cable exit openings of the enclosure mold, ensuring a proper waterproofing of the connection between the cables and the connection pins <NUM>.

Preferably, the enclosure mold comprises protruding reserves which, when the enclosure mold is closed, cover a sealing portion <NUM> of each electric cable <NUM> contained within the enclosure mold preventing the sealing portions <NUM> to be embedded in the enclosure <NUM>. The protruding reserves are separated from the cable exit openings of the enclosure mold through a distance in which a portion of the electric cables will be overmolded.

In this case, the electric cables <NUM> are positioned within the enclosure mold positioning a sealing portion <NUM> of each electric cable <NUM> in correspondence with the complementary protruding reserves of the enclosure mold, producing an enclosure with a sealing portion <NUM> of each cable <NUM> exposed and comprised between two portions of the electric cables embedded in the enclosure <NUM>.

Claim 1:
A waterproof electromagnetic device, comprising:
a magnetic core (<NUM>) surrounded by at least one coil (<NUM>);
an electronic circuit board (<NUM>) including at least connection pins (<NUM>) electrically connected to the at least one coil (<NUM>);
an enclosure (<NUM>) overmolded on a waterproof manner surrounding the magnetic core (<NUM>), the at least one coil (<NUM>) and the electronic circuit board (<NUM>);
characterized in that
the magnetic core (<NUM>) further includes several protrusions (<NUM>) projecting from the magnetic core (<NUM>) towards an external surface of the enclosure (<NUM>), so that a centering of the magnetic core (<NUM>) within the enclosure (<NUM>) is provided during the overmoulding operation.