Trailer coupling comprising a sensor

1. A trailer coupling for a motor vehicle comprising a coupling arm for attaching a trailer or for carrying a load carrier, and comprising at least one sensor for detecting a deformation, caused by a load engaged on a bearing element of the trailer coupling, whereby at least one recess for the at least one sensor is provided on the bearing element, whereby the at least one sensor is provided for measuring a distance of reference surfaces of the at least one recess, wherein the reference surfaces move toward or away from one another during the deformation of the bearing element and extend in a transverse manner to a support section of the bearing element, which deforms during the application of stress by the load or is free from the flow of forces as a result of the support section of the bearing element, which is transferred from the support section by the load engaged on the bearing element.

2. The trailer coupling according to claim 1 , wherein the reference surfaces extend in a longitudinal or transverse manner relative to a direction of a flow of forces through the support section.

3. The trailer coupling according to claim 1 , wherein the at least one recess on at least one protrusion protruding in front of a base body of the bearing element or indicator element is provided.

4. The trailer coupling according to claim 1 , wherein the at least one recess is slit-shaped, and has a transverse width of less than 5 mm, and extends over the entire transverse width of the bearing element.

5. The trailer coupling according to claim 1 , wherein an expansion cavity is arranged between the support section and the reference surfaces, a transverse width of said expansion cavity is greater in one direction parallel to the distance between the reference surfaces than the distance between the reference surfaces.

6. The trailer coupling according to claim 5 , wherein the at least one recess and the expansion cavity have an overall T-shaped or oval or egg-shaped or keyhole-shaped design.

7. The trailer coupling according to claim 5 , wherein the at least one recess communicates with a sensor support in which an evaluation device to evaluate at least one signal of the at least one sensor is arranged or can be arranged.

8. The trailer coupling according to claim 7 , wherein the sensor support is formed from the expansion cavity or forms the expansion cavity.

9. The trailer coupling according to claim 7 , wherein the sensor support communicates with at least one passage opening by means of which a screw can be pierced in order to connect the passage opening with the components of the at least on sensor arranged in the sensor support.

10. The trailer coupling according to claim 1 , wherein the at least one recess comprises at least two recesses arranged on the bearing element one after the other relative to a direction of a flow of forces exerted by the support section or wherein the at least one recess is arranged on a curved section or a straight section of the bearing element.

11. The trailer coupling according to claim 1 , wherein the coupling arm has at least one mounting opening which is provided on a transverse side of the bearing element, which is at an angle to the reference surfaces.

12. The trailer coupling according to claim 1 , wherein a capacitive or inductive or optic sensor element of the at least one sensor is firmly attached to at least one reference surface or wherein two reference surfaces are each allocated to one sensor element whereby the sensor elements are at a distance from one another and can be moved relative to one another.

13. The trailer coupling according to claim 1 , wherein at least one sensor element of the at least one sensor is arranged on a bracketing section of a bearing part, which has a fixing section that is at an angle relative to the bracketing section that extends adjacent to the bracketing section, the bracketing section being connected to a fixing area of the bearing element adjacent to the reference surfaces.

14. The trailer coupling according to claim 13 , wherein the bearing part has an L-shaped design or the bracketing section and the fixing section are formed from sides of the bearing part which are at an angle relative to one another.

15. The trailer coupling according to claim 1 , wherein at least two sensor elements of the at least one sensor are arranged adjacent to one another on at least one reference surface of the reference surfaces of the at least one recess in a first row direction or at least two row directions at an angle to one another.

16. The trailer coupling according to claim 1 , wherein the at least one sensor has a capacitive sensor element or an inductive sensor element or an expansion measuring strip or a distance sensor or an optic sensor element or a piezo element or a sensor housing in which at least one expansion measurement strip or a capacitive measurement surface are arranged in a manner protected against environmental influences.

17. The trailer coupling according to claim 1 , wherein the recess forms or comprises an expansion joint.

18. The trailer coupling according to claim 1 , wherein at least one of the reference surfaces is provided on a tongue-like or arm-like indicator element or a protrusion.

19. The trailer coupling according to claim 1 , wherein the at least one recess comprises a hollow which extends from an opening on an external surface of the bearing element, whereby the reference surfaces are orthogonal, to the opening.

20. The trailer coupling according to claim 1 , wherein the at least one recess is arranged on each opposite side of the support section or the recess has a broader zone arranged adjacent to the reference surfaces or a broader groove base arranged adjacent to the reference surfaces.