Device for pulling a trailer and/or retaining a load carrying unit
In order to improve a device for pulling a trailer and/or retaining a load carrying unit that is mountable at the rear end of a motor vehicle body and which comprises a supporting arm that is connected by a first end region to the motor vehicle body and is provided at a second end region with an element for attaching the trailer and/or for fixing the load carrying unit and furthermore which comprises sensors for capturing reversible deformations of the supporting arm caused by loads on the supporting arm in such a manner as to provided a device with which an allocation of captured elongations to individual applications of force is possible in as simple a way as possible, it is proposed that strain sensors which are affected by reversible deformations thereof be assigned to a supporting arm section of the supporting arm, and that, for capturing at least one selected bending strain, at least one strain sensor be arranged on one side and at least one strain sensor on an opposite side of a surface region of a neutral reference surface assigned to the selected bending load and that each of the strain sensors be arranged at a distance from this surface region.
1 . A device for pulling a trailer or retaining a load carrying unit that is mountable at the rear end of a motor vehicle body, comprising: a supporting arm which is connected to the vehicle body by a first end region and is provided at a second end region with an element for attaching the trailer and/or for fixing the load carrying unit, and furthermore comprising sensors for capturing reversible deformations of the supporting arm caused by loads on the supporting arm,
strain sensors of the supporting arm section which are affected by the reversible deformations thereof capture at least one selected bending load, at least one strain sensor is arranged on one side and at least one strain sensor is arranged on an opposite side of a neutral reference surface of the selected bending load and the strain sensors are each arranged at distances that may be the same or different from the neutral reference surface, each bending load defines a specific neutral reference surface, the supporting arm is subject to a vertical bending load and a transverse bending load, whereby in the case of a vertical bending load the specific neutral reference surface that is formed is a vertical neutral reference surface and in the case of a transverse bending load the specific neutral reference surface that is formed is a transverse neutral reference surface, an evaluating unit is provided which evaluates the signals of the strain sensors, which determines the force acting on the element in the vertical direction and which determines a horizontal transverse force.
2 . A device in accordance with claim 1 , wherein a vertical projection of each of the strain sensors that are arranged on mutually opposite sides of the neutral reference surface lies on the neutral reference surface.
3 . A device in accordance with claim 2 , wherein, the vertical projection of each of the strain sensors on the neutral reference surface defines a surface region on the neutral reference surface, wherein in each of the directions of extent thereof, the surface region exhibits an extent which is maximally double the extent of each of the strain sensors parallel to this direction of extent.
4 . A device in accordance with claim 1 , wherein the strain sensors arranged on mutually opposite sides of the respective neutral reference surface are arranged at distances from the respective neutral reference surface which are such that the distance to the at least one strain sensor on one side of the of the neutral reference surface lies within the range of 0.5 times up to 1.5 times the distance to the at least one strain sensor on the opposite side of the neutral reference surface.
5 . A device in accordance with claim 1 , wherein the strain sensors are aligned approximately parallel with the neutral reference surface.
6 . A device in accordance with claim 1 , wherein the strain sensors are arranged on sensor carrier surfaces running approximately parallel to the neutral reference surface and are connected thereto.
7 . A device in accordance with claim 1 , wherein the selected bending load is caused by a force on the element in the vertical direction and in that the neutral reference surface arising therefrom is a vertical neutral reference surface.
8 . A device in accordance with claim 1 , wherein the strain sensors are arranged and aligned in such a manner that they capture a horizontal tensile load by a horizontal longitudinal force on the element.
9 . A device in accordance with claim 1 , wherein the section of the supporting arm is fixed in such a manner that the neutral reference surface of this section of the supporting arm comprises a component in a horizontal longitudinal direction.
10 . A device in accordance with claim 9 , wherein the neutral reference surface of this supporting section runs substantially parallel to the horizontal longitudinal direction.
11 . A device in accordance with claim 1 , wherein the supporting arm is a ball neck which, at its second end, carries an element in the form of a coupling ball that serves for attaching a trailer and/or fixing a load carrying unit.
12 . A device in accordance with claim 1 , wherein a curved piece is provided between an intermediate region of the supporting arm comprising the section of the supporting arm and the first end region and/or the second end region of the supporting arm.
13 . A device in accordance with claim 1 , wherein the section of the supporting arm lies in a central region between the first end region and the second end region of the supporting arm.
14 . A device in accordance with claim 1 , wherein the evaluating unit determines a horizontal longitudinal force.
15 . A device in accordance with claim 1 , wherein the evaluating unit includes an acceleration sensor.