Sensor and method for producing the sensor

#This application claims the benefit of German Patent Application Serial No. 10 2011 102 952.8, filed May 23, 2011; German Patent Application Serial No. 10 2011 105 172.8, filed Jun. 9, 2011; and German Patent Application Serial No. 10 2011 112 826.7, filed Sep. 12, 2011, all of which are hereby incorporated herein in their entirety.

#The invention relates to an inductively operating sensor, particularly for measuring distances and positions of a metallic object.

#Inductive sensors are used in many technical fields for measuring tasks, monitoring machines and devices, or for process automation. Generally it is distinguished between simple switching sensors and continuous distance sensors. The first ones are also called proximity switches, because in case a metallic object approaches they produce a switching signal at a certain distance. The second group however delivers a continuous, distance-related signal when an object approaches, thus these sensors are used for measuring distances and positions.

#There are various options to implement and further develop the teaching of the present invention in an advantageous manner. For this purpose, on the one hand reference is made to the dependent claims provided herein and on the other hand to the following explanation of preferred exemplary embodiments of the invention using the drawing. In the context of the explanation of preferred exemplary embodiments of the invention using the drawing the teaching of the generally preferred embodiments and further developments of the teaching are also explained. The drawing shows:

#FIGS. 1a and 1b in a schematic view an exemplary embodiment of a sensor according to the invention, in which the core is inserted into a recess of the film body,

#FIG. 1c in a schematic view another exemplary embodiment of the sensor according to the invention in which the coil body with the core is inserted in the core and glued here,

#FIG. 1 shows a first exemplary embodiment of an inductive sensor. The coil comprises circuit board tracks in a multi-layered ceramic system. The ceramic is embodied such that in the rear part, i.e. facing away from the front of the sensor element, a recess is provided accepting the ferrite core. The recess is based on the shape of the coil. This may be embodied either circularly or rectangular. Other shapes are also possible, e.g., triangular arrangements. In order to yield a maximum packing density of the coil the circuit board tracks should show a narrow width and a short distance from each other.

#In order to increase inductivity even further the ferrite core is inserted into the recess. The shape of the coil and the ferrite core are adjusted to each other such that no air gap develops between the ferrite and the ceramic, to the extent possible. This may represent e.g., a conventional ferrite of sintered powered ferrite, for example a cup core. Other standard forms are also possible for the ferrite core, such as P-cores, PM-cores, or E-cores. It is important that the multi-layered ceramic is adjusted to the shape. Here it must be observed that the ceramic shrinks during sintering, which must be considered when determining the shape.

#Another possibility for the core material are materials with particularly high permeability, for example Mu-metal foils that can be stacked onto each other.