Magnetic core element, magnetic core module and an inductive component using the magnetic core module

#The present invention relates to a magnetic core element, a magnetic core module and an inductive component using the magnetic core module for the construction of antennae having an improved coverage, in particular antennae for locking and unlocking a motor vehicle, and for the position detection.

#Wireless electronic locking and unlocking systems are known from the automobile industry. For example, magnetic antennae are installed in automobile door handles, in door frames, side panels or bumpers of motor vehicles, to transmit or receive an electromagnetic signal in order to allow a wireless communication, e.g. for communicating with a transceiver of a key. To accommodate a transmit-receive antenna in a bent door handle the magnetic core is designed, for example, as a rod core of a longitudinal shape, which is formed of several tape-shaped layers of a soft-magnetic metal alloy, wherein the bending tolerance of the layer stack goes from limited to small. Therefore, the core of these antennae may be subjected to stress, resulting in altered magnetic properties if the deformation is too strong, as great tensile forces and compressive forces occur in the material in the layer levels. Moreover, the basis materials of these so-called tape cores are significantly more expensive than those for ferrite cores, and the magnetic losses of more inexpensive, iron-based amorphous cores, as compared to ferrites, are clearly greater at frequencies above 100 kHz. Conventional methods for the production of those antennae using tape cores additionally have the drawback that the stacking of the tapes is relatively complicated.

#Antennae with cores made of ferrite rods that have a bent or very long shape are difficult to realize, or not at all, due to the production method. Examples for a bent ferrite core rod are described in DE 101 28 406 B4 and DE 10 2007 007 117 A1. The production of a ferrite core requires the mixing of a presintered magnetic powder with a special plastic injection granulate, which is injected to obtain the desired shape.

#In the drawings:

#FIG. 1 shows a schematic perspective view of a first embodiment illustrating a magnetic core element of the present invention;

#FIG. 2 shows a schematic cross-sectional view of a variably adjustable, bent connection of at least two magnetic core elements according to the present invention;

#FIG. 1 shows a magnetic core element 100 according to an embodiment of the present invention. The magnetic core element is rod-shaped and defines a longitudinal direction 101, and comprises a first end 102 with a spherical recess 110 and a second end 103 with a spherical connecting protrusion 120, which is suited for the production of a variably adjustable, bent connection of at least two magnetic core elements 100. The core diameter of the magnetic core element 100 is typically 1 mm to 10 mm, and preferably has a length of 10 to 60 mm. It will be appreciated, however, that the dimensions of the magnetic core elements are to be chosen depending on the specific field of application.

#In one embodiment of the present invention the spherical recess 110 comprises a spherical shell, and the spherical connecting protrusion 120 comprises a spherical head, to form a cup/sphere end contour. In comparison with a beveled, plane end section surface known in the prior art, the spherical surface of the connecting protrusion has a larger surface area, proving to be advantageous for a variably adjustable, bent connection of at least two magnetic core elements 100. On the one hand, a more stable adhesion between the at least two magnetic core elements 100, respectively, the plurality of magnetic core elements 100 is achieved when same are connected, by which for example the frequency of breakages at the adhesive joints between two magnetic core elements 100 respectively can be reduced. This is a particular advantage as, depending on the intended purpose and structural requirements, a plurality of magnetic core elements 100 can be joined for use in an antenna. A bent connection of at least two magnetic core elements 100, respectively, a plurality of magnetic core elements 100 can be installed, for example, in the handles of motor vehicle doors, in door frames, side panels or bumpers of motor vehicles. On the other hand, the realization of a cup/sphere end contour preferably ensures a connection of the at least two magnetic core elements 100 without adhesive bonding. The bonding of the magnetic core elements without an adhesive will be described in more detail below.

#Apart from the kind of stabilizing the end shape of the rod core, composed of several elements, for use in an antenna it should be noted that, when joining at least two or more magnetic core elements 100, it is possible to realize different final antenna configurations due to the cup/sphere end contour. In other words, the magnetic core elements 100 can be joined to form a straight or bent rod core, or to a combination thereof. As the cup/sphere end contour is rotationally symmetric about the longitudinal axis there will be no limitation with respect to the mutual position when connecting at least two magnetic core elements 100. Thus, a rod core joined from several magnetic core elements 100 can adopt different physical shapes.