Device for coupling a trailer and / or a load carrier unit

Abstract

The invention relates to a method and a device for operating a device, which can be mounted on the rear side of a motor vehicle body, for coupling a trailer and / or a load carrier unit, comprising a retaining arm which is securely connected to the motor vehicle body at a first end during operation and supports a coupling element for the trailer and / or the load carrier unit at a second end, wherein, during operation, forces acting on the coupling element and transmitted from the retaining arm to the motor vehicle body are detected by an evaluation unit by means of deformation sensors, wherein the retaining arm has at least two deformation regions, wherein the respective deformation behaviour thereof with a force acting on the retaining arm is detected by at least one deformation sensor, which is rigidly coupled to the respective deformation region of the retaining arm and thereby detects the deformation behaviour thereof.

Description

[0001] DEVICE FOR COUPLING A TRAILER AND / OR A LOAD CARRIER UNIT

[0002] The invention relates to a method for operating a device that can be mounted on the rear of a motor vehicle body for coupling a trailer and / or a load carrier unit, comprising a holding arm that is firmly connected to the motor vehicle body at a first end during operation and carries a coupling element for the trailer and / or the load carrier unit at a second end, wherein forces acting on the coupling element and transmitted from the holding arm to the motor vehicle body are detected by an evaluation unit using deformation sensors, wherein the holding arm has at least two deformation regions, the deformation behavior of which, when a force acts on the holding arm, is detected by at least one deformation sensor, which is rigidly coupled to the respective deformation region of the holding arm and thereby detects its deformation behavior, characterized in thatthat the evaluation unit has a load analysis stage which, based on deformation values ​​of the at least two deformation regions determined by the deformation sensors, determines at least one load type of the holding arm using analysis methods.

[0003] The advantage of the solution according to the invention is therefore that it makes it possible to analyze load types on the holding arm and to differentiate between load types in order to be able to provide information about the effects of the load on the coupling element on the vehicle, for example.

[0004] It is particularly advantageous if the load analysis stage uses deformation values ​​without transforming them into a force in the vertical direction and / or a force in the vehicle's longitudinal direction and / or a force transverse to the vehicle's longitudinal center plane.

[0005] An advantageous solution provides that the at least one analysis method is a value comparison method, i.e. a method that analyses various determined or stored deformation values ​​by comparing them with other values.

[0006] It is particularly advantageous if the value comparison procedure involves comparing the deformation values ​​with each other and / or with reference values ​​in order to determine whether these meet various analysis criteria.

[0007] In particular, it is advantageously provided that the reference values ​​in the load analysis stage are predetermined, in particular stored, reference values.

[0008] In principle, the reference values ​​can be determined theoretically or through model calculations.

[0009] However, it is particularly advantageous if the reference values ​​are determined through experiments.

[0010] In particular, it is advantageous if the reference values ​​are determined by load tests of a representative holding arm.

[0011] With regard to the implementation of the analysis procedures, a wide variety of approaches are conceivable.

[0012] An advantageous solution provides for the evaluation of absolute values ​​of the load-induced deformation values ​​in at least one of the analysis methods. Load-induced deformation values ​​are defined as deformation values ​​recorded by the deformation sensors when the support arm is loaded and—if deemed necessary—corrected with respect to the deformation values ​​recorded by a zero-load detection system.

[0013] For example, one analysis criterion is based on a comparison of the absolute values ​​of the load-induced deformation values ​​with threshold values ​​as reference values.

[0014] Another advantageous solution provides that at least one further analysis criterion is based on a comparison of each of the absolute values ​​of the load-related deformation values ​​with a stored reference value range.

[0015] However, this stored reference value range is either determined theoretically or preferably by tests, in particular by load tests on a representative holding arm.

[0016] A further advantageous solution provides that, for at least one analysis criterion, at least one deformation value of a deformation region is compared with a deformation value of at least one other deformation region.

[0017] In particular, such an analysis method compares the behavior of the deformation value of a deformation range that is highly sensitive to support load relative to a deformation range that is weakly sensitive to support load.

[0018] The method according to the invention can be carried out particularly advantageously if an analysis criterion is based on a comparison of the behavior of at least one of the deformation values ​​of a deformation range that is highly sensitive to support load relative to at least one of the deformation values ​​of a deformation range that is weakly sensitive to support load.

[0019] Conclusions can be drawn from this comparison using a variety of other analytical methods.

[0020] A simple solution is to determine the difference between the two deformation values ​​in the analysis procedure.

[0021] This difference between the two deformation values ​​could in principle be compared with predefined reference value ranges.

[0022] However, it is particularly advantageous if the analysis method determines the ratio of the difference between the two deformation values ​​relative to the largest of the two deformation values.

[0023] This ratio could also be compared with specified reference values.

[0024] It is particularly advantageous if the analysis criterion is based on the ratio of the difference between the two deformation values ​​to the largest of the deformation values ​​in comparison with stored reference value ranges.

[0025] Each of the analysis criteria explained above allows, for example, a simple distinction to be made between the fact that a trailer is attached to the coupling element and the fact that a load carrier, in particular a bicycle carrier, is attached to the coupling element.

[0026] For example, in a trailer, the load-related deformation value or the load-related deformation values ​​of a deformation range highly sensitive to the vertical load are above a threshold value, and the load-related deformation value or the load-related deformation values ​​of a deformation range weakly sensitive to the vertical load are below the threshold value. In contrast, in a bicycle rack, the load-related deformation value or the load-related deformation values ​​of both deformation ranges are above the threshold value.

[0027] Furthermore, in the case of a trailer, the load-related deformation value or the load-related deformation values ​​of the weakly support load-sensitive deformation range lie within a reference value range that includes the deformation value zero, while the load-related deformation value or the load-related deformation values ​​of the strongly support load-sensitive deformation range lie outside the reference value range.

[0028] In addition, the ratio of the difference between the load-related deformation values ​​of the highly support load-sensitive deformation range and the weak support load-sensitive deformation range to the largest of the deformation values ​​for a trailer lies in a reference value range with higher values ​​than for a bicycle carrier, where the reference value range of this ratio lies below the reference value range for the trailer.

[0029] A further advantageous method provides that an analysis method determines the magnitude of the forces acting on at least one deformation area by comparing the respective load-related deformation value with at least one load reference value specified for this.

[0030] It is particularly advantageous if, in this method, the assignment of the at least one load-related deformation value to at least three load reference values ​​is carried out by assigning the at least one deformation value to the areas between two consecutive load reference values.

[0031] Preferably, it is provided that an analysis criterion is based on the absolute value of at least one of the load-related deformation values ​​relative to the series of at least three load reference values ​​assigned to this deformation value.

[0032] A further advantageous method provides that in an analysis method a comparison is carried out of at least one of the load-related deformation values ​​with an associated maximum load reference value.

[0033] In this case, it is preferably provided that an analysis criterion is based on the absolute value of at least one of the load-related deformation values ​​relative to the maximum load reference value assigned to this at least one load-related deformation value.

[0034] With these analysis criteria, the loads on the support arm can be determined without the need for a transformation of the deformation values ​​and a subsequent analysis of the forces F x , F y and F z necessary, at least in a general way, namely by recording the allocation of the load-related deformation values ​​to a range between two consecutive load reference values ​​or to the exceeding or approaching of the maximum load reference value.

[0035] A further advantageous method provides that at least one load-related deformation value is recorded in a time-resolved manner during the analysis method.

[0036] Preferably, in this method, an analysis criterion is based on a temporal progression of at least one of the deformation values.

[0037] This temporal profile can, for example, be a brief temporal change in at least one of the deformation values, i.e., an increase in at least one of the deformation values ​​over time, in order to detect a brief, particularly sudden, impact on the coupling element. Such a brief, sudden impact on the coupling element occurs in particular when the trailer's braking effect is not as desired, for example, when a trailer's braking system is defective.

[0038] For example, such a short-term sudden impact occurs in a time window of less than 0.5 seconds.

[0039] In this case, it is particularly intended that a gradient behavior is recorded from at least one load-related deformation value.

[0040] In such a case, an analysis criterion focuses in particular on the slope steepness of the gradient behavior, which it compares with a reference value.

[0041] If the slope is greater than the reference value, the trailer's behavior is problematic.

[0042] Another possibility for recording the time-resolved behavior of the load-related deformation values ​​is, alternatively or additionally, that the analysis method determines a time duration of an increase from at least one load-related deformation value up to a maximum value.

[0043] In this case, the analysis criterion is whether the duration exceeds or falls short of a reference time, whereby the reference time is preferably less than 0.5 seconds.

[0044] If the time period is less than the reference time, the trailer is behaving problematically.

[0045] The above analysis criteria for the time-resolved recording of at least one of the load-related deformation values ​​make it possible to detect impulse-like effects of a trailer on the support arm, in particular on its coupling element, and thus a possible problematic behavior of the trailer, for example a malfunctioning overrun brake.

[0046] Another advantageous embodiment of the analysis method provides that in the analysis method a temporal course of an oscillation of at least one of the deformation values ​​around a mean value of this oscillating deformation value is detected, and in particular an amplitude and / or period duration is detected.

[0047] An advantageous embodiment of the method according to the invention provides that an analysis criterion evaluates an amplitude of oscillations of one of the load-related deformation values ​​around a mean value and compares it with a reference value.

[0048] In addition or alternatively, another solution provides that an analysis criterion is based on a comparison of a period of one of the load-related deformation values ​​with a reference period.

[0049] The analysis of the temporal course of oscillations of at least one of the deformation values ​​makes it possible to decide, in particular by analyzing the size of the amplitude and / or the period, whether a trailer attached to the coupling element performs irrelevant movements or serious and therefore dangerous swaying movements for the towing vehicle, for example in the case of an amplitude above the reference value or a period above the reference period.

[0050] To improve the function of the load analysis stage, it is preferably provided that each deformation value used by the load analysis stage is corrected by a zero-load correction stage. Such a zero-load correction stage provides, for example, that a deformation value is determined at zero load and subtracted from a determined deformation value under load, so that each deformation value under load is corrected with respect to the proportion of the deformation value under zero load.

[0051] Preferably, the solution according to the invention provides that the zero load correction stage is activated before the holding arm is loaded.

[0052] Another advantageous solution provides that the zero load correction stage is activated after the holding arm has been moved into a working position.

[0053] Furthermore, it is preferably provided that each deformation value used by the load analysis stage is corrected by an inclination correction stage which corrects the actual orientation of the support arm due to an inclination of the vehicle in relation to a deformation value when the support arm is aligned with a vehicle standing on a horizontal reference surface.

[0054] Preferably, the inclination correction stage provides that the deformation values ​​of the deformation regions are changed in such a way that the influence of the changed orientation of the support arm relative to an orientation of the support arm when a vehicle is standing on a horizontal reference surface is taken into account.

[0055] For example, it is intended that the inclination correction stage works with stored inclination correction values.

[0056] For practical purposes, the inclination correction values ​​are determined experimentally. In particular, the inclination correction values ​​are determined experimentally by recording them for a loaded and unloaded support arm at various inclinations.Alternatively or in addition to the above solutions, the object mentioned at the outset is achieved according to the invention by a method for detecting the force on a device which can be mounted at the rear of a motor vehicle body for coupling a trailer or a load carrier unit, comprising a holding arm which is firmly connected to the motor vehicle body at a first end during operation and is designed to carry a coupling element at a second end, wherein the holding arm is provided with a sensor arrangement, wherein in this method according to the invention the holding arm is provided with at least two deformation sensors which react in particular in different ways to three forces acting on the coupling element in spatial directions running transversely to one another, and that the at least two deformation sensors supply deformation values ​​from which at least one force component acting on the coupling element is determined.

[0057] The advantage of the solution according to the invention is that it makes it possible to determine reliable values ​​for the effective force in a simple manner.

[0058] It is particularly advantageous if at least one of the values ​​of the force components running in these spatial directions is determined.

[0059] It is particularly advantageous if at least the value of the force component running in the direction of gravity is determined.

[0060] Furthermore, it is advantageous if at least the value of the force component running in the direction of travel of the motor vehicle is determined.

[0061] Furthermore, it is advantageous if at least the value of the force component running transversely, in particular perpendicular to a vertical longitudinal center plane, is determined. To avoid incorrect determinations of the deformation values ​​and / or the values ​​of the force components acting on the coupling element, it is preferably provided that, before determining the deformation values ​​and / or the values ​​of the force components, a check is carried out to determine whether a suitable condition for determining the force components acting on the coupling element exists.

[0062] A wide variety of criteria can be used for this purpose.

[0063] A favorable solution provides that by detecting at least one of the parameters such as voltage supply, in particular the deformation sensors, vehicle orientation in space, i.e. a vehicle orientation such that it is essentially on a horizontal plane, as well as the presence of the working position of the holding arm, it is checked whether a suitable condition for determining the deformation values ​​and / or the force component on the coupling element exists.

[0064] In order to avoid falsification of the deformation values ​​and / or the values ​​of the force components, it is advantageous to record at least one of the respective values ​​in the case of a zero load before determining the respective values.

[0065] Furthermore, it is advantageous if the respective values ​​are recorded at zero load after the holding arm has been moved into a working position, so that it can be avoided that the respective values ​​are determined outside the working position, which would lead to incorrect results.

[0066] Furthermore, an advantageous solution, alternatively or additionally, provides for the respective values ​​to be recorded at zero load after the coupling element has been mounted on the support arm, provided the coupling element is not permanently connected to the support arm, in order to also avoid incorrect measurements. Furthermore, it is provided that the respective values ​​at zero load are only saved if the values ​​fall below specified values ​​that exclude an external force acting on the coupling element, thus enabling a plausibility check to rule out incorrect recording of the zero load.

[0067] A further advantageous solution provides that the respective values ​​are recorded at zero load after detecting an approach to an object, in particular to a trailer or a load carrier.

[0068] Finally, it is preferably provided that after the respective values ​​have been recorded at no load, the values ​​are recorded again at no load after a predetermined period of time in order to ensure that the values ​​recorded at no load are not retained permanently and thus incorrect measurements can occur.

[0069] In order to obtain the most accurate load-related values ​​of the force components, it is preferably provided that, in order to determine at least one of the load-related deformation values ​​and / or values ​​of the force components, the corresponding values ​​supplied at zero load are subtracted from the values ​​supplied when a force is applied to the coupling element.

[0070] In order to also avoid incorrect determinations of the force on the coupling element, the determination of the force on the coupling element can be carried out in particular when it is ensured as far as possible that the condition of the motor vehicle and the device according to the invention allows the force on the coupling element to be determined as accurately as possible.

[0071] For example, it is provided that at least one of the deformation values ​​and / or the values ​​of the force components on the coupling element is determined if an on-board function of the motor vehicle is carried out, i.e. the motor vehicle is in an operational state, but not in a standby state or, for example, in a switched-off state.

[0072] A further advantageous solution provides that a determination of at least one of the deformation values ​​and / or the values ​​of the force components on the coupling element is carried out if a plug has been inserted into a socket assigned to the holding arm.

[0073] Inserting the plug into the socket assigned to the holding arm can be interpreted as a signal that an object is engaging the holding arm, in particular its coupling element, and thus exerting a force on it.

[0074] A further expedient solution provides that at least one of the deformation values ​​and / or the values ​​of the force components on the coupling element is determined after the detection of an object acting on the coupling element, in particular a trailer or a load carrier.

[0075] This detection of an object engaging the coupling element can be carried out, for example, by means of a camera system or a sensor arrangement, preferably an ultrasonic sensor arrangement, which are usually provided anyway to facilitate reversing with the motor vehicle.

[0076] Another practical solution provides for the determination of at least one of the deformation values ​​and / or the values ​​of the force components acting on the coupling element when the speed of the motor vehicle is less than 5 km per hour, particularly when the motor vehicle is stationary, so that the occurrence of dynamic forces can be excluded and it can be ensured that only static forces acting on the coupling element are recorded. After determining at least one of the deformation values ​​and / or the values ​​of the force components, this is transmitted in a variety of ways.

[0077] Preferably, it is provided that at least one of the values ​​is transmitted when the force component acts on the coupling element in the vertical direction.

[0078] Furthermore, it is advantageous if at least one of the values ​​is transmitted for a force component acting on the coupling element in the direction of travel and in particular parallel to a vertical longitudinal center plane.

[0079] Finally, a further expedient solution provides that at least one of the values ​​is transmitted for a force component acting transversely to a vertical longitudinal center plane of the holding arm, in particular in an approximately horizontal direction.

[0080] In addition, the transmission of the deformation values ​​and / or the values ​​of the respective force components can be carried out in a variety of ways.

[0081] One possibility is that at least one of the deformation values ​​and / or the values ​​of the respective force component and in particular the measurement accuracy associated with it is displayed, i.e. is displayed on a presentation unit, for example a display.

[0082] This makes it easier for a user of the motor vehicle to quickly recognize the quality of the determination of the deformation values ​​and / or the value of the respective force component and to draw the necessary conclusions for moving the vehicle.

[0083] In order to enable a rapid evaluation of the deformation values ​​and / or the values ​​of the force component, one solution in particular provides that at least one of the values ​​of the respective force component is displayed qualitatively in order to enable a rapid assessment of the forces acting on the device according to the invention without detailed study.

[0084] A further advantageous solution provides that the value of a force component acting on the coupling element in the vertical direction is displayed in relation to a predetermined support load for the respective motor vehicle.

[0085] Furthermore, an advantageous solution provides that the value for a force component acting in the direction of travel is displayed in relation to a maximum tractive force in order to also simplify the effect of the forces acting on the vehicle for a user.

[0086] A further advantageous solution provides that at least one of the values ​​of the force components acting on the coupling element is transmitted to an electronic stabilization system of the motor vehicle, so that it is possible to easily take into account the forces acting from the trailer or the load carrier during the electronic stabilization of the vehicle.

[0087] In addition, an advantageous solution provides that the value of force components acting on the coupling element is transmitted to a chassis control system of the motor vehicle.

[0088] In connection with the previous explanation of the individual embodiment variants of the method according to the invention, no further details were given as to how the values ​​of force components acting on the coupling element are linked to the deformation values.

[0089] One advantageous solution involves linking the values ​​of the force components acting on the coupling element to the deformation values ​​using transformation coefficients. Such a link represents a simple mathematical solution that takes the various relationships into account.

[0090] In particular, it is intended that the deformation values ​​supplied by the deformation sensors are linked to the values ​​of the force components in the three spatial directions running transversely to each other by means of the transformation coefficients of a transformation matrix.

[0091] No further details have been provided so far regarding the determination of the transformation coefficients of the transformation matrix.

[0092] An advantageous solution provides that the transformation coefficients of the transformation matrix are determined as part of a calibration process.

[0093] Such a calibration process provides, for example, that when a defined force component acts on the coupling element, the deformation values ​​supplied by the deformation sensors are recorded, whereby during the calibration process different force components on the coupling element are used one after the other to generate different deformation values.

[0094] In particular, it is provided that during the calibration process, a defined force component is applied to the coupling element in one of the three spatial directions running transversely to each other and that the deformation values ​​supplied by the deformation sensors are recorded.

[0095] In particular, the calibration can be carried out advantageously if, during the calibration process, each force component acting in one of the three spatial directions has the same amount, wherein in particular the individual force components act on the coupling element one after the other in order to obtain the respective deformation values ​​for each of the individual force components.

[0096] A particularly simple mathematical model provides that the transformation coefficients are determined under the assumption of a linear relationship between the values ​​of the force components in the three spatial directions running transversely to each other and the deformation values ​​provided by the deformation sensors.

[0097] Alternatively or in addition, it is also conceivable to determine the transformation coefficients using other methods, for example using the least squares method.

[0098] A particularly simple procedure provides that the spatial directions running transverse to each other run perpendicular to each other.

[0099] An improved procedure for determining the values ​​of the force components provides that, starting from the coupling element as the center, the space around the coupling element is divided into eight octants defined by the three spatial directions running transversely to each other, that in order to determine the set of transformation coefficients in each of the octants, the coupling element is acted upon by force components which lie within the respective octant, that the deformation values ​​are recorded and that octant-based transformation coefficients are determined for these force components in the respective octant.

[0100] However, in order to be able to use the octant-based transformation coefficients, it is preferably provided that one of the transformation matrices, this can be a non-octant-based transformation matrix or one of the octant-based transformation matrices, is used to determine the values ​​of the force components on the coupling element and then it is checked to which of the octants the force components are to be assigned and then a new determination of the values ​​of the force components is carried out using the transformation matrix assigned to this octant.

[0101] Alternatively or in addition to the solutions described above, the object is also achieved according to the invention in a device of the type described at the outset in that forces acting on the coupling element during operation and transmitted from the holding arm to the motor vehicle body are detected by an evaluation unit with a sensor arrangement which has at least three deformation sensors and in that in particular the at least three deformation sensors of the sensor arrangement are arranged on the same side of a neutral fiber of the holding arm which is not deformed during a bending deformation of the holding arm.

[0102] The advantage of the solution according to the invention is that it makes it possible to easily detect the deformations of the holding arm with the sensor arrangement.

[0103] Furthermore, the object mentioned at the outset is also achieved by a device according to claims 40 to 79.

[0104] Alternatively or in addition to the solutions described above, the object is also achieved according to the invention in a device of the type described at the outset in that forces acting on the coupling element during operation and transmitted from the holding arm to the motor vehicle body are detected by an evaluation unit with a sensor arrangement which has at least two deformation sensors and in that in particular the at least two deformation sensors of the sensor arrangement are arranged on the same side of a neutral fiber of the holding arm which is not deformed during a bending deformation of the holding arm.

[0105] The advantage of the solution according to the invention lies in the fact that it makes it possible to easily detect the deformations of the support arm using the sensor arrangement. It is particularly advantageous if all sensors of the sensor arrangement are arranged on the same side of the neutral fiber of the support arm, which is not deformed when the support arm deforms.

[0106] The object mentioned at the outset is further achieved according to the invention in a device of the type described at the outset in that a force detection module is arranged on one side of the holding arm, said force detection module comprising a sensor arrangement which detects forces acting on the coupling element during operation and forces transmitted from the holding arm to the motor vehicle body.

[0107] Such a force detection module represents an advantageous, simple solution for detecting the forces acting on the holding arm.

[0108] In particular, it is provided that the sensor arrangement of the force detection module has at least three, in particular four, deformation sensors.

[0109] No further details have been provided so far regarding the arrangement of the motor vehicle module.

[0110] Thus, an advantageous solution provides that the force detection module is not arranged on any side of the support arm facing a roadway in the operating state, i.e. that the force detection module is arranged only on the sides of the support arm that do not face the roadway, since this prevents the force detection module from being damaged by contact of the support arm with objects arranged on a roadway or on a surface.

[0111] It is particularly advantageous if the force sensing module is arranged on a side of the support arm facing away from the roadway during operation. This arrangement of the force sensing module has the advantage that this side is the least susceptible to damage for the force sensing module.

[0112] In order to be able to advantageously arrange the deformation sensors on the one hand and to advantageously transmit the deformations of the holding arm to the deformation sensors on the other hand, a further solution to the problem mentioned at the outset preferably provides that forces acting on the coupling element during operation and transmitted from the holding arm to the motor vehicle body are detected by an evaluation unit with a sensor arrangement which has at least two deformation sensors, that the deformation sensors are arranged on at least one deformation transmission element which is connected to the holding arm.

[0113] The deformations can be arranged on different deformation transmission elements.

[0114] In a further solution to the problem mentioned at the outset, it is particularly advantageous if forces acting on the coupling element during operation and transmitted from the holding arm to the motor vehicle body are detected by an evaluation unit with a sensor arrangement which has at least two deformation sensors, and if all deformation sensors of the sensor arrangement are arranged on a common deformation transmission element.

[0115] A particularly advantageous detection of the forces acting on the holding arm is possible in particular if each of the at least two deformation sensors detects deformations of different magnitudes of the holding arm when the same force acts on the coupling element, since this allows differently directed forces that can act on the coupling element to be easily separated. With regard to the connection of the deformation transmission element to the holding arm, it is preferably provided that the deformation transmission element is connected to the holding arm at least two fastening areas in a relatively motionless and thus rigid manner, and that at least one of the deformation sensors is arranged between the fastening areas of the deformation element.

[0116] It is even more advantageous if the deformation transmission element is connected to the holding arm by at least three fastening areas and if at least one of the deformation sensors is arranged between each two of the fastening areas.

[0117] No further details have been provided so far regarding the connection of the fastening areas of the deformation transmission element to the holding arm.

[0118] In principle, it is conceivable to connect the fastening areas directly to the holding arm, for example by welding them to it.

[0119] However, a particularly advantageous solution provides that the deformation transmission element is connected to the holding arm in the fastening areas by means of connecting elements.

[0120] Such a connection to the holding arm by means of the connecting elements can be realized particularly favorably if the connecting elements are rigidly connected to the holding arm on the one hand and rigidly connected to the fastening areas of the deformation transmission element on the other hand.

[0121] A particularly advantageous solution provides that the connecting elements are formed, in particular in one piece, onto the holding arm.

[0122] When providing such a connection between the holding arm and the deformation transmission element, it is preferably provided that the connecting elements transmit deformations of the holding arm in deformation regions of the holding arm located between the connecting elements to the fastening regions of the deformation transmission element.

[0123] In particular, it is advantageous if there is a deformation area of ​​the holding arm between each two connecting elements.

[0124] A particularly advantageous solution in terms of design provides that the holding arm has at least two deformation regions, the deformations of which are transmitted via connecting elements arranged on both sides of the respective deformation region to fastening regions of the deformation transmission element, between which a deformation-affected region of the deformation transmission element lies.

[0125] With regard to the arrangement of the two deformation regions in the holding arm, it is particularly advantageous if the at least two deformation regions are arranged successively in an extension direction of the holding arm.

[0126] Furthermore, in order to detect the deformations in the deformation-affected regions, it is advantageous if at least one deformation sensor is arranged in one of the deformation-affected regions of the deformation transmission element.

[0127] In particular, at least one deformation sensor is arranged in each of the deformation-affected regions of the deformation transmission element.

[0128] Furthermore, it is expediently provided that each deformation-prone region is connected to a deformation-resistant region of the deformation-transmitting element, and that the fastening regions are each located in a deformation-resistant region, so that they are encompassed by the respective deformation-resistant region. A deformation-resistant region is understood in particular to mean that it has a significantly higher rigidity than a deformation-prone region, i.e., at least by a factor of two, even better, at least by a factor of five.

[0129] This solution has the advantage that the largest possible part of the deformations transmitted from the deformation areas of the holding arm to the deformation transmission element is not distributed over the entire deformation transmission element, but essentially affects the deformation-affected areas, in order to achieve the greatest possible deformation in these deformation-affected areas, in which in particular the deformation sensors are arranged, and to have the smallest possible deformation or no deformation in the deformation-resistant areas of the deformation transmission element.

[0130] It is particularly advantageous if the deformation-prone areas are arranged between two deformation-resistant areas.

[0131] Furthermore, for an optimal shift of as much of the deformation transmitted to the deformation transmission element as possible to the deformation-affected regions, it is advantageous if the deformation-resistant regions and the deformation-affected regions are arranged consecutively in a deformation direction, that is, if the deformation-resistant regions and the deformation-affected regions are arranged consecutively in the direction in which the essential deformation is transmitted to the deformation transmission element.

[0132] Furthermore, it is advantageous if the deformation-affected regions are designed as deformation concentration regions.

[0133] A deformation concentration area is to be understood in particular as meaning that the predominant part, i.e. more than 50%, even better more than 70%, of the deformations transmitted to or acting on the deformation transmission element develop in this area.

[0134] Such a design of the deformation-affected areas has the advantage that the deformations can essentially be concentrated in them and thus the largest possible deformations can be detected by the respective deformation sensors.

[0135] No further details have been provided so far regarding the material of the deformation transmission element.

[0136] Thus, it is preferably provided that the material of the deformation transmission element outside the deformation-affected regions is designed as a deformation-resistant or deformation-inert material, which means that, for example, outside the deformation-affected regions, less than 30%, even better less than 20%, preferably less than 10%, of the deformations transmitted to or acting on the deformation transmission element form.

[0137] On the other hand, it is preferably provided that the material of the deformation transmission element is inclined to deformation or suitable for deformation in the deformation-prone regions by a suitable shaping, for example a cross-sectional constriction.

[0138] In order to be able to compensate for deformations of the deformation transmission element that are not caused by the deformations of the holding arm, it is preferably provided that the deformation transmission element has, in addition to the respective deformation-affected region, a deformation-free region on which at least one reference deformation sensor is arranged.

[0139] In a deformation-free region, due to its design and arrangement, essentially none, that is to say in particular less than 20%, even better less than 10% and preferably less than 5%, of the deformations transmitted or acting on the deformation transmission element occur.

[0140] With such a reference deformation sensor in a deformation-free area, it is possible to detect material deformations in the deformation transmission element caused by influences other than the deformations transmitted or acting on the deformation transmission element, which deformations arise, for example, due to thermal influences, via the reference deformation sensors and then, since these are also detected by the deformation sensor, to correct them.

[0141] For this reason, it is preferably provided that the respective deformation-free region is made of the same material as the deformation-affected region.

[0142] Furthermore, it is preferably provided that the respective deformation-free region is connected on one side to a deformation-resistant region of the deformation transmission element.

[0143] A particularly advantageous geometric design provides that the deformation-free area of ​​the deformation transmission element is tongue-shaped.

[0144] Furthermore, it is preferably provided that the deformation-free region of the deformation transmission element is made of the same material, in particular with the same material thickness, as the deformation-affected region.

[0145] In order to achieve an optimal coupling between the effects detected by the reference deformation sensors and the effects detected by the deformation sensors, it is preferably provided that the reference deformation sensors are thermally coupled to the deformation transmission element.

[0146] In particular, this makes it possible for the reference deformation sensors to be thermally coupled to the deformation sensors by means of the deformation transmission element.

[0147] In particular, in the case where a reference deformation sensor is assigned to each deformation sensor, optimal thermal coupling is achieved when, between the respective deformation sensor and the reference deformation sensor assigned to it, each deformation-affected region provided with a deformation sensor is thermally coupled to the deformation-free region assigned to it and carrying the assigned reference deformation sensor.

[0148] Overall, it is advantageous if the deformation-free area carrying the respective reference deformation sensor has the same thermal behavior as the deformation-affected area carrying the corresponding deformation sensor.

[0149] In order to have as many of the same deformations as possible in the area of ​​the reference deformation sensor as in the area of ​​the deformation sensor, it is expediently provided that the respective deformation-free area carrying the reference deformation sensor has a geometric shape that is comparable, preferably identical, to the deformation-affected area carrying the deformation sensor.

[0150] In particular, it is also advantageous if the deformation-free region of the deformation transmission element is made of the same material as the deformation-affected region of the deformation transmission element. To monitor the functionality of the reference deformation sensors, it is preferably provided that at least one temperature sensor is assigned to the reference deformation sensors for function monitoring.

[0151] It is even better if each of the reference deformation sensors is assigned a temperature sensor for function monitoring.

[0152] No further details have been provided so far regarding the design of the deformation transmission element.

[0153] Thus, an advantageous solution provides that the deformation transmission element is designed in a plate-like manner and each deformation-affected region carrying a deformation sensor is formed by a cross-sectional constriction of the deformation transmission element.

[0154] In particular, it is provided that the cross-sectional constriction of the deformation transmission element is formed by a constriction of a surface extension of the deformation transmission element.

[0155] The deformation sensors and the reference deformation sensors can be sensors of various designs that can detect stretching and / or compression processes in the deformation-affected areas.

[0156] One possibility is that the deformation sensors and the reference deformation sensors are designed as strain sensors, in particular strain gauges.

[0157] Another possibility is for the deformation sensors and the reference deformation sensors to be designed as magnetostrictive or optical sensors that detect strain and compression. For optimal compensation of a strain sensor, it is particularly advantageous if the reference strain sensor assigned to it is identical to the assigned strain sensor.

[0158] The object mentioned at the outset is also achieved according to the invention in particular in that the holding arm has a first deformation region and a second deformation region between the first end and the second end, which, when a force acts parallel to the direction of travel in the longitudinal center plane of the holding arm, each experience deformations which differ from the deformations when a force acts in the longitudinal center plane and transversely to the direction of travel.

[0159] The advantage of the solution according to the invention is that because the first and the second deformation region behave differently, i.e. deform to different degrees, when subjected to a force acting in the longitudinal center plane of the support arm and parallel to the direction of travel and a force acting in the longitudinal center plane and transversely, in particular perpendicularly, to the direction of travel, in particular with the same amount of force, it is possible, due to these different deformations of the first deformation region and the second deformation region, to differentiate between a force acting in the longitudinal center plane of the support arm and parallel to the direction of travel and a force acting in the longitudinal center plane of the support arm and transversely to the direction of travel when evaluating the signals from the deformation sensors.

[0160] It is even more advantageous if the first and second deformation regions also behave differently, i.e., deform to different degrees, when subjected to a force acting transversely, in particular perpendicularly, to the longitudinal center plane, in particular with an equal magnitude to the forces acting in the longitudinal center plane and parallel to the direction of travel or transversely thereto. The different behavior of the first and second deformation regions can be achieved by a different shape, in particular different cross-sections and / or a different profile and / or a different length of the first and second deformation regions in the support arm.

[0161] In particular, it is provided that the first and second deformation regions are arranged successively in an extension direction of the holding arm.

[0162] With regard to the processing of the signals from the deformation sensors and the reference deformation sensors, no further details have been given in connection with the previous explanation of the solution according to the invention.

[0163] An advantageous solution provides that each deformation sensor is connected to the associated reference deformation sensor in a Wheatstone bridge.

[0164] This allows for the simple compensation of effects, in particular thermal effects, which are not caused by the deformation of one of the deformation areas of the holding arm by directly using the signals from the deformation sensor and the reference deformation sensor.

[0165] Furthermore, an advantageous solution provides that the evaluation unit has a processor that converts the values ​​corresponding to the deformations in the deformed areas using transformation values ​​determined by calibration and stored in a memory into the corresponding values ​​of forces acting on the coupling element in three transverse, in particular perpendicular, spatial directions. This makes it possible to determine the forces acting on the coupling element in three transverse, in particular perpendicular, spatial directions from the values ​​corresponding to the deformations.

[0166] It is particularly advantageous if two of the forces run parallel to, in particular in the longitudinal center plane of the holding arm, but transversely, in particular perpendicularly, to each other and if the third force runs transversely, in particular perpendicularly, to the longitudinal center plane of the holding arm.

[0167] An improvement in the conversion of the values ​​corresponding to the deformations is possible if transformation values ​​for force combinations acting on the coupling element in different octants are stored in the memory, since these different transformation values ​​allow an optimized adaptation to the actual conditions.

[0168] In particular, an evaluation unit according to the solution according to the invention is designed such that the values ​​of deformation sensors and, in particular, if appropriate, also reference deformation sensors are recorded to determine the deformations.

[0169] In order to also have the possibility of carrying out a functional test of the reference deformation sensors, it is provided that the evaluation unit includes values ​​from at least one temperature sensor for the functional test of the reference deformation sensors.

[0170] It is even better if the evaluation unit records values ​​from a temperature sensor assigned to the respective reference deformation sensor in order to test the function of the reference deformation sensors.

[0171] The at least one temperature sensor or temperature sensors can be arranged either on a circuit board carrying the evaluation unit or on the deformation transmission element. In the above embodiments, it was not explained in detail how the holding arm and the coupling element can be connected to each other.

[0172] An advantageous solution provides that the holding arm carries the coupling element at its second end.

[0173] In this case, it is particularly advantageous if the holding arm and the coupling element form a continuous part so that a separation between the holding arm and the coupling element is not possible.

[0174] In particular, in such a case, it is provided that the holding arm is designed as a ball neck and carries the coupling element comprising a coupling ball at the second end.

[0175] A further advantageous solution provides that the holding arm comprises a receiving body which is designed to releasably receive the coupling element.

[0176] The coupling element can, for example, be part of a support system for coupling it to the support arm.

[0177] The coupling element is designed, for example, as a coupling element of a carrier system for goods, in particular luggage or bicycles.

[0178] In particular, the receiving body is designed such that it has a plug-in receptacle which is accessible through an insertion opening.

[0179] In a receiving body of the holding arm as described above, it is preferably provided that the coupling element comprises a support arm.

[0180] The support arm is preferably provided with a plug-in section that can be inserted into the plug-in receptacle and secured there. The support arm then becomes part of the support system, for example.

[0181] Alternatively, in a further embodiment, the support arm is designed to carry a coupling ball.

[0182] In a further embodiment, the support arm is provided with other coupling devices, for example with a coupling mouth.

[0183] For precise fixing of the support arm, it is expedient if the insertion section is positively received in the insertion receptacle transversely to an insertion direction and is fixed in the functional state in the insertion direction by a positive-locking body.

[0184] The above description of solutions according to the invention thus includes in particular the various combinations of features defined by the following numbered embodiments:

[0185] 1. A method for operating a device that can be mounted on the rear of a motor vehicle body for coupling a trailer and / or a load carrier unit (360), comprising a holding arm (30) that is firmly connected to the motor vehicle body (12) at a first end (32) during operation and carries a coupling element (40) for the trailer (350) and / or the load carrier unit (360) at a second end, wherein forces acting on the coupling element (40) and transmitted from the holding arm (30) to the motor vehicle body (12) are detected by an evaluation unit (230) by means of deformation sensors (172, 174, 176, 178), wherein the holding arm (30) has at least two deformation regions (82, 84), the deformation behavior of which, when a force acts on the holding arm (30), is each detected by at least one deformation sensor (172, 174, 176, 178) is recorded, which corresponds to the respective deformation area (82,84) of the support arm (30) and thereby detects its deformation behavior, wherein the evaluation unit (230) has a load analysis stage (233) which, based on deformation values ​​(D152, D154, D156, D2158) of the at least two deformation regions (82, 84) determined by the deformation sensors (172, 174, 176, 178), determines at least one load type of the support arm (30) using analysis methods.

[0186] 2. Method according to embodiment 1, wherein the load analysis stage (233) calculates the deformation values ​​(D152, D154, D156, D158) without transforming them into forces in the vertical direction (F z ) and / or in the vehicle longitudinal direction (24) and / or transversely to the vehicle longitudinal center plane (F y ) is used.

[0187] 3. Method according to one of the preceding embodiments, wherein the at least one analysis method is a value comparison method.

[0188] 4. Method according to one of the preceding embodiments, wherein in the value comparison method the deformation values ​​(D) are compared with one another and / or with reference values ​​(RBO, S, RAWB, RFWB, B1...B6, RFS, ZR, RAS, RPS).

[0189] 5. Method according to embodiment 4, wherein the reference values ​​are predetermined, in particular stored, reference values ​​(RBO, S, RAWB, RFWB, B1...B6, RFS, ZR, RAS, RPS).

[0190] 6. The method according to embodiment 4 or 5, wherein the reference values ​​(RBO, S, RAWB, RFWB, B1...B6, RFS, ZR, RAS, RPS) are determined by experiments.

[0191] 7. The method according to embodiment 6, wherein the reference values ​​are determined by load tests of a representative support arm (30). 8. The method according to one of the preceding embodiments, wherein absolute values ​​of the load-induced deformation values ​​(D) are evaluated in at least one analysis method.

[0192] 9. Method according to embodiment 8, wherein an analysis criterion is based on a comparison of the absolute values ​​of the load-induced deformation values ​​(D) with threshold values ​​(S) as reference values.

[0193] 10. Method according to embodiment 8 or 9, wherein at least one analysis criterion is based on a comparison of each of the absolute values ​​of the load-induced deformation values ​​(D) with a stored reference value range (RBO).

[0194] 11. Method according to one of the preceding embodiments, wherein in at least one analysis method at least one deformation value (D) of a deformation region (82) is compared with at least one deformation value (D) of the at least one other deformation region (84).

[0195] 12. Method according to one of the preceding embodiments, wherein the analysis method is based on a comparison of the behavior of the deformation values ​​(D152, D154) of a highly support load-sensitive deformation region relative to a weak support load-sensitive deformation region.

[0196] 13. Method according to embodiment 11 or 12, wherein the analysis method determines the difference between the two deformation values ​​(D).

[0197] 14. The method according to embodiment 13, wherein the analysis method determines the ratio of the difference between the two deformation values ​​(D) relative to the largest of the two deformation values ​​(D).

[0198] 15. Method according to one of embodiments 11 to 14, wherein an analysis criterion is based on a comparison of the behavior of at least one deformation value (D152, D154) of a highly support load-sensitive deformation region (82) relative to at least one deformation value (D154, D156) of a weakly support load-sensitive deformation region (84).

[0199] 16. Method according to embodiment 15, wherein the analysis criterion is based on the ratio of the difference of the deformation values ​​(D) to the largest of the two deformation values ​​(D) in comparison with stored reference value ranges (RAWB, RFWB).

[0200] 17. Method according to one of the preceding embodiments, wherein the size of the load-related deformation value (D152, D154, D156, D158) determined in at least one deformation region (82, 84) is determined by an analysis method by comparing this load-related deformation value (D152, D154, D156, D158) with at least one load reference value (B1...B6) predetermined for this deformation value.

[0201] 18. Method according to embodiment 17, wherein in the analysis method the assignment of the at least one load-related deformation value (D152, D154, D156, D158) to a plurality of predetermined load reference values ​​(B1...B6) is carried out in that the at least one actual deformation value (D152, D154, D156, D158) is assigned to the areas (BS1, BS2, BS3, BS4, BS5) between two successive load reference values ​​(B1...B6).

[0202] 19. Method according to embodiment 17 or 18, wherein an analysis criterion is based on the assignment of at least one of the deformation values ​​relative to the series of at least three load reference values ​​(B1 to B6) provided for this deformation value.

[0203] 20. The method according to any one of the preceding embodiments, wherein an analysis method involves comparing at least one of the deformation values ​​(D152, D154, D156, D158) with an associated maximum load reference value (B6). 21. The method according to embodiment 20, wherein an analysis criterion is based on the assignment of the load-related deformation value to at least one of the load-related deformation values ​​(D152, D154, D156, D158) relative to a maximum load reference value (B6) associated with the deformation value.

[0204] 22. Method according to one of the preceding embodiments, wherein an analysis method records at least one of the load-related deformation values ​​(D152, D154, D156, D158) in a time-resolved manner.

[0205] 23. The method according to embodiment 22, wherein an analysis criterion is based on a short-term temporal change of at least one of the deformation values ​​(D152, D154, D156, D158).

[0206] 24. Method according to embodiment 23, wherein in the analysis method a gradient behavior of at least one of the actual deformation values ​​(D152, D154, D156, D158) is detected.

[0207] 25. The method according to embodiment 24, wherein an analysis criterion compares a slope steepness (FS) of the gradient behavior with a stored reference value (RFS).

[0208] 26. Method according to embodiments 22 to 25, wherein in the analysis method a time duration (Z) of an increase of at least one of the load-related deformation values ​​(D) up to a maximum value is determined.

[0209] 27. The method according to any one of embodiments 22 to 26, wherein an analysis criterion is based on comparing the time period (Z) with a reference time (RZ). 28. The method according to any one of embodiments 22 to 27, wherein an analysis criterion is based on a temporal progression of at least one of the deformation values.

[0210] 29. Method according to one of embodiments 22 to 28, wherein in the analysis method a temporal course of an oscillation of at least one of the deformation values ​​(D152, D154, D156, D158) around a mean value of this oscillating deformation value (D152, D154, D156, D158) is detected.

[0211] 30. The method according to embodiment 29, wherein an analysis criterion is based on a comparison of an amplitude (AS) of oscillations of one of the load-induced deformation values ​​(D152, D154, D156, D158) around the mean value with a reference value (RAS).

[0212] 31. Method according to embodiments 28 to 30, wherein an analysis criterion is based on a comparison of a period duration (PS) of one of the load-related deformation values ​​with a reference period duration (RPS).

[0213] 32. Method according to the preamble of embodiment 1 or according to one of the preceding embodiments, wherein each deformation value (D) used by the load analysis stage (233) is corrected by a zero load correction stage (285).

[0214] 33. Method according to embodiment 32, wherein a deformation value (DI) at zero load is determined by the zero load correction stage (285) and subtracted from a determined deformation value (D) under load.

[0215] 34. The method according to embodiment 32 or 33, wherein the zero-load correction stage (285) is activated before a load is applied to the support arm (30). 35. The method according to any one of embodiments 32 to 34, wherein the zero-load correction stage (285) is activated after a movement of the support arm (30) into a working position.

[0216] 36. Method according to one of the preceding embodiments, wherein each deformation value (D) used by the load analysis stage (233) is corrected by an inclination correction stage (283) which corrects the actual orientation of the support arm (30) due to an inclination of the vehicle in relation to a deformation value (D) in an orientation of the support arm (30) with a vehicle standing on a horizontal reference surface.

[0217] 37. Method according to embodiment 36, wherein the inclination correction stage (283) changes the deformation values ​​(D) of the deformation regions (152, 154, 156, 158) in such a way that the influence of the changed orientation of the support arm (30) relative to an orientation of the support arm (30) in a vehicle standing on a horizontal reference surface is taken into account.

[0218] 38. Method according to embodiment 36 or 37, characterized in that the inclination correction stage (283) operates with stored inclination correction values.

[0219] 39. The method of embodiment 38, wherein the tilt correction stage (283) operates with experimentally determined tilt correction values.

[0220] 40. A device mountable at the rear of a motor vehicle body for coupling a trailer and / or a load carrier unit (360), comprising a holding arm (30) which is firmly connected to the motor vehicle body (12) at a first end (32) during operation and carries a coupling element (40) for the trailer (350) and / or the load carrier unit (360) at a second end, wherein forces acting on the coupling element (40) and transmitted from the holding arm (30) to the motor vehicle body (12) are detected by an evaluation unit (230) by means of deformation sensors (172, 174, 176, 178), wherein the holding arm (30) has at least two deformation regions (82, 84), the deformation behavior of which, when a force acts on the holding arm (30), is each detected by at least one deformation sensor (172, 174, 176, 178) is recorded, which corresponds to the respective deformation area (82,84) of the holding arm (30) is rigidly coupled and thereby detects its deformation behavior, wherein the evaluation unit (230) has a load analysis stage (233) which, based on deformation values ​​(D152, D154, D156, D2158) of the at least two deformation regions (82, 84) determined by the deformation sensors (172, 174, 176, 178), determines at least one load type of the holding arm (30) using analysis methods.

[0221] 41. Device according to embodiment 40, wherein the load analysis stage (233) calculates the deformation values ​​(D152, D154, D156, D158) without transforming them into forces in the vertical direction (F z ) and / or in the vehicle longitudinal direction (24) and / or transversely to the vehicle longitudinal center plane (F y ) is used.

[0222] 42. Device according to one of embodiments 40 to 41, wherein the at least one analysis method is a value comparison method.

[0223] 43. Device according to one of embodiments 40 to 42, wherein in the value comparison method the deformation values ​​(D) are compared with each other and / or with reference values ​​(RB0, S, RAWB, RFWB, B1...B6, RFS, ZR, RAS, RPS).

[0224] 44. The device according to embodiment 43, wherein the reference values ​​are predetermined, in particular stored, reference values ​​(RB0, S, RAWB, RFWB, B1...B6, RFS, ZR, RAS, RPS). 45. The device according to embodiment 43 or 44, wherein the reference values ​​(RB0, S, RAWB, RFWB, B1...B6, RFS, ZR, RAS, RPS) are determined by experiments.

[0225] 46. ​​Device according to embodiment 45, wherein the reference values ​​are determined by load tests of a representative holding arm (30).

[0226] 47. Device according to one of embodiments 40 to 46, wherein in at least one analysis method absolute values ​​of the load-induced deformation values ​​(D) are evaluated.

[0227] 48. Device according to embodiment 47, wherein an analysis criterion is based on a comparison of the absolute values ​​of the load-induced deformation values ​​(D) with threshold values ​​(S) as reference values.

[0228] 49. Device according to embodiment 47 or 48, wherein at least one analysis criterion is based on a comparison of each of the absolute values ​​of the load-induced deformation values ​​(D) with a stored reference value range (RBO).

[0229] 50. Device according to one of embodiments 40 to 49, wherein in at least one analysis method at least one deformation value (D) of a deformation region (82) is compared with at least one deformation value (D) of the at least one other deformation region (84).

[0230] 51. Device according to one of embodiments 40 to 50, wherein the analysis method is based on a comparison of the behavior of the deformation values ​​(D152, D154) of a highly support load-sensitive deformation region relative to a weak support load-sensitive deformation region.

[0231] 52. The device according to embodiment 50 or 51, wherein the analysis method determines the difference between the two deformation values ​​(D). 53. The device according to embodiment 52, wherein the analysis method determines the ratio of the difference between the two deformation values ​​(D) relative to the largest of the two deformation values ​​(D).

[0232] 54. Device according to one of embodiments 50 to 53, wherein an analysis criterion is based on a comparison of the behavior of at least one deformation value (D152, D154) of a highly support load-sensitive deformation region (82) relative to at least one deformation value (D154, D156) of a weakly support load-sensitive deformation region (84).

[0233] 55. Device according to embodiment 54, wherein the analysis criterion is based on the ratio of the difference of the deformation values ​​(D) to the largest of the two deformation values ​​(D) in comparison with stored reference value ranges (RAWB, RFWB).

[0234] 56. Device according to one of embodiments 40 to 55, wherein the size of the load-related deformation value (D152, D154, D156, D158) determined in at least one deformation region (82, 84) is determined by an analysis method by comparing this load-related deformation value (D152, D154, D156, D158) with at least one load reference value (B1...B6) predetermined for this deformation value.

[0235] 57. Device according to embodiment 56, wherein in the analysis method the assignment of the at least one load-related deformation value (D152, D154, D156, D158) to a plurality of predetermined load reference values ​​(B1...B6) is carried out in that the at least one actual deformation value (D152, D154, D156, D158) is assigned to the areas (BS1, BS2, BS3, BS4, BS5) between two successive load reference values ​​(B1...B6).

[0236] 58. Device according to embodiment 56 or 57, wherein an analysis criterion is based on the assignment of at least one of the deformation values ​​relative to the series of at least three load reference values ​​(B1 to B6) provided for this deformation value.

[0237] 59. Device according to one of embodiments 40 to 58, wherein in an analysis method a comparison of at least one of the deformation values ​​(D152, D154, D156, D158) with an associated maximum load reference value (B6) is carried out.

[0238] 60. Device according to embodiment 59, wherein an analysis criterion is based on the assignment of the load-related deformation value to at least one of the load-related deformation values ​​(D152, D154, D156, D158) relative to a maximum load reference value (B6) assigned to the deformation value.

[0239] 61. Device according to one of embodiments 40 to 60, wherein an analysis method records at least one of the load-related deformation values ​​(D152, D154, D156, D158) in a time-resolved manner.

[0240] 62. Device according to embodiment 61, wherein an analysis criterion is based on a short-term temporal change of at least one of the deformation values ​​(D152, D154, D156, D158).

[0241] 63. Device according to embodiment 62, wherein in the analysis method a gradient behavior of at least one of the actual deformation values ​​(D152, D154, D156, D158) is detected.

[0242] 64. Apparatus according to embodiment 63, wherein an analysis criterion compares a slope steepness (FS) of the gradient behavior with a stored reference value (RFS).

[0243] 65. The device according to embodiments 61 to 64, wherein the analysis method determines a time duration (Z) of an increase of at least one of the load-related deformation values ​​(D) up to a maximum value. 66. The device according to any one of embodiments 61 to 65, wherein an analysis criterion is based on comparing the time duration (Z) with a reference time (RZ).

[0244] 67. Device according to one of embodiments 61 to 66, wherein an analysis criterion is based on a temporal course of at least one of the deformation values.

[0245] 68. Device according to one of embodiments 61 to 67, wherein in the analysis method a temporal course of an oscillation of at least one of the deformation values ​​(D152, D154, D156, D158) around a mean value of this oscillating deformation value (D152, D154, D156, D158) is detected.

[0246] 69. Device according to embodiment 68, wherein an analysis criterion is based on a comparison of an amplitude (AS) of oscillations of one of the load-induced deformation values ​​(D152, D154, D156, D158) around the mean value with a reference value (RAS).

[0247] 70. Device according to embodiments 67 to 69, wherein an analysis criterion is based on a comparison of a period (PS) of one of the load-induced deformation values ​​with a reference period (RPS).

[0248] 71. Device according to the preamble of embodiment 40 or according to any one of embodiments 40 to 68, wherein each deformation value (D) used by the load analysis stage (233) is corrected by a zero load correction stage (285).

[0249] 72. The device according to embodiment 71, wherein the zero-load correction stage (285) determines a deformation value (DI) at zero load and subtracts it from a determined deformation value (D) under load. 73. The device according to embodiment 71 or 72, wherein the zero-load correction stage (285) is activated before a load is applied to the holding arm (30).

[0250] 74. Device according to one of embodiments 71 to 73, wherein the zero load correction stage (285) is activated after a movement of the holding arm (30) into a working position.

[0251] 75. Device according to one of embodiments 40 to 74, wherein each deformation value (D) used by the load analysis stage (233) is corrected by an inclination correction stage (283) which corrects the actual orientation of the support arm (30) due to an inclination of the vehicle in relation to a deformation value (D) in an orientation of the support arm (30) with a vehicle standing on a horizontal reference surface.

[0252] 76. Device according to embodiment 75, wherein the inclination correction stage (283) changes the deformation values ​​(D) of the deformation regions (152, 154, 156, 158) in such a way that the influence of the changed orientation of the support arm (30) relative to an orientation of the support arm (30) in a vehicle standing on a horizontal reference surface is taken into account.

[0253] 77. Device according to embodiment 75 or 76, wherein the inclination correction stage (283) operates with stored inclination correction values.

[0254] 78. Apparatus according to embodiment 77, wherein the tilt correction stage (283) operates with experimentally determined tilt correction values.

[0255] 79. Device according to the preamble of embodiment 40 or according to one of embodiments 40 to 78, wherein the at least two deformation sensors (172, 174, 176, 178) of the sensor arrangement (170) are arranged on the same side of a neutral fiber of the holding arm whose length is not variable during a bending deformation of the holding arm (30). 80. Device according to embodiment 79, wherein a force detection module (100) is arranged on one side of the holding arm (30, 30'), comprising a sensor arrangement (170) which, during operation, detects forces acting on the coupling element (40) and transmitted from the holding arm (30) to the motor vehicle body (12).

[0256] 81. Device according to embodiment 80, wherein the sensor arrangement has at least three, in particular four deformation sensors (172, 174, 176).

[0257] 82. Device according to embodiment 80 or 81, wherein the force detection module (100) is not arranged on any side of the holding arm (30, 30') facing a roadway (44) in the operating state.

[0258] 83. Device according to one of embodiments 80 to 82, wherein the force detection module (100) is arranged in the operating state on a side of the holding arm (30, 30') facing away from a roadway (44).

[0259] 84. Device according to the preamble of embodiment 40 or according to one of embodiments 40 to 83, wherein during operation forces acting on the coupling element (40) and transmitted from the holding arm (30) to the motor vehicle body (12) are detected by an evaluation unit (230) with a sensor arrangement (170) which has at least two deformation sensors (172, 174, 176), that the deformation sensors (172, 174, 176, 178) are arranged on at least one deformation transmission element (102) which is connected to the holding arm (30).

[0260] 85. Device according to the preamble of embodiment 40 or according to one of embodiments 40 to 84, wherein during operation forces acting on the coupling element (40) and transmitted from the holding arm (30) to the motor vehicle body (12) are detected by an evaluation unit (230) with a sensor arrangement (170) which has at least two deformation sensors (172, 174, 176), that all deformation sensors (172, 174, 176, 178) of the sensor arrangement (170) are arranged on a common deformation transmission element (102).

[0261] 86. Device according to one of embodiments 79 to 85, wherein each of the at least two deformation sensors (172, 174, 176) detects different large deformations of the holding arm (30, 30') when one and the same force acts on the coupling element (40).

[0262] 87. Device according to one of embodiments 79 to 86, wherein the deformation transmission element (102) is connected to the holding arm (30) in a relatively movement-free and thus rigid manner at at least two fastening regions (104, 106, 108) and that at least one of the deformation sensors (172, 174, 176, 178) is arranged between the fastening regions (104, 106, 108) of the deformation transmission element (102).

[0263] 88. Device according to one of embodiments 79 to 87, wherein the deformation transmission element (102) is connected to the holding arm (30) by at least three fastening regions (104, 106, 108) and that at least one of the deformation sensors (172, 174, 176, 178) is arranged between each two of the fastening regions (104, 106, 108).

[0264] 89. Device according to one of embodiments 79 to 88, wherein the deformation transmission element (102) is connected in the fastening regions (104, 106, 108) to the holding arm (30) by means of connecting elements (114, 116, 118).

[0265] 90. Device according to embodiment 89, wherein the connecting elements (114, 116, 118) are rigidly connected on the one hand to the holding arm (30) and on the other hand to the fastening regions (104, 106, 108) of the deformation transmission element (102).

[0266] 91. Device according to embodiment 90, wherein the connecting elements (114, 116, 118) are integrally formed on the holding arm (30). 92. Device according to one of embodiments 79 to 91, wherein the connecting elements (114, 116, 118) transfer deformations of the holding arm (30) in deformation regions (82, 84) of the holding arm (30) located between the connecting elements (114, 116, 118) to the fastening regions (104, 106, 108) of the deformation transmission element (102).

[0267] 93. Device according to one of embodiments 89 to 92, wherein a deformation region (82, 84) of the holding arm (30) is located between each two connecting elements (114, 116, 118).

[0268] 94. Device according to one of embodiments 79 to 93, wherein the holding arm (30) has at least two deformation regions (82, 84), the deformations of which are transmitted via connecting elements (114, 116, 118) arranged on both sides of the respective deformation region (82, 84) to fastening regions (104, 106, 108) of the deformation transmission element (102), between which a deformation-affected region (152, 154, 156) of the deformation transmission element (102) lies.

[0269] 95. Device according to embodiment 94, wherein the at least two deformation regions (82, 84) are arranged successively in an extension direction of the holding arm (30).

[0270] 96. Device according to one of embodiments 79 to 95, wherein at least one deformation sensor (172, 174, 176, 178) is arranged in one of the deformation-affected regions (152, 154, 156, 158) of the deformation transmission element (102).

[0271] 97. Device according to one of embodiments 94 to 96, wherein each deformation-prone region (152, 154, 156, 158) is connected to a deformation-resistant region (144, 146, 148) of the deformation-transmitting element (102), and wherein the fastening regions (104, 106, 108) are each located in a deformation-resistant region (144, 146, 148). 98. Device according to embodiment 97, wherein the deformation-prone regions (152, 154, 156, 158) are each arranged between two deformation-resistant regions (144, 146, 148).

[0272] 99. Device according to embodiment 97 or 98, wherein the deformation-resistant regions (144, 146, 148) and the deformation-prone regions (152, 154, 156, 158) are arranged successively in a deformation direction.

[0273] 100. Device according to one of embodiments 94 to 99, wherein the deformation-affected regions (152, 154, 156, 158) are formed as deformation concentration regions.

[0274] 101. Device according to one of embodiments 79 to 100, wherein the material of the deformation transmission element (102) outside the deformation-affected regions (152, 154, 156, 158) is formed as a deformation-resistant or deformation-inert material.

[0275] 102. Device according to one of embodiments 79 to 101, wherein the material of the deformation transmission element (102) is prone to deformation in the deformation-prone regions (152, 154, 156, 158) due to a shaping, for example a cross-sectional constriction.

[0276] 103. Device according to one of embodiments 79 to 102, wherein the deformation transmission element (102) has, in addition to the respective deformation-affected region (152, 154, 156, 158), a deformation-free region (192, 194, 196, 198), on which at least one reference deformation sensor (182, 184, 186, 188) is arranged.

[0277] 104. The device according to embodiment 103, wherein the respective deformation-free region (192, 194, 196, 198) is formed from the same material as the deformation-affected region (152, 154, 156, 158). 105. The device according to embodiment 103 or 104, wherein the respective deformation-free region (192, 194, 196, 198) is connected on one side to a deformation-resistant region (144, 146, 148) of the deformation transmission element (102).

[0278] 106. Device according to one of embodiments 103 to 105, wherein the deformation-free region (192, 194, 196, 198) of the deformation transmission element (102) is tongue-shaped.

[0279] 107. Device according to one of embodiments 103 to 106, wherein the deformation-free region (192, 194, 196, 198) of the deformation transmission element (102) is made of the same material, in particular with the same material thickness, as the deformation-affected region (152, 154, 156, 158).

[0280] 108. Device according to one of embodiments 103 to 107, wherein the reference deformation sensors (182, 184, 186, 188) are thermally coupled to the deformation transmission element (102).

[0281] 109. The device according to embodiment 108, wherein the reference deformation sensors (182, 184, 186, 188) are thermally coupled to the deformation sensors (172, 174, 176, 178) by means of the deformation transmission element (102).

[0282] 110. Device according to embodiment 109, wherein for optimal thermal coupling between the respective deformation sensor (172, 174, 176, 178) and the reference deformation sensor (182, 184, 186, 188) assigned thereto, each deformation-affected region (152, 154, 156, 158) provided with a deformation sensor (172, 174, 176, 178) is thermally coupled to the deformation-free region (192, 194, 196, 198) assigned thereto and carrying the assigned reference deformation sensor (182, 184, 186, 188). 111. Device according to one of embodiments 103 to 110, wherein the deformation-free region (192, 194, 196, 198) carrying the respective reference deformation sensor (182, 184, 186, 188) has the same thermal behavior as the deformation-affected region (152, 154, 156, 158) carrying the corresponding deformation sensor (172, 174, 176, 178).

[0283] 112. Device according to one of embodiments 103 to 111, wherein the respective deformation-free region (192, 194, 196, 198) carrying the reference deformation sensor (182, 184, 186, 188) has a geometric shape that is comparable to the deformation-affected region (152, 154, 156, 158) carrying the deformation sensor (172, 174, 176, 178).

[0284] 113. Device according to one of embodiments 103 to 112, wherein the deformation-free region (192, 194, 196, 198) of the deformation transmission element (102) is made of the same material as the deformation-affected region (152, 154, 156, 158) of the deformation transmission element (102).

[0285] 114. Device according to one of embodiments 103 to 113, wherein at least one temperature sensor (252, 254, 256, 258) is assigned to the reference deformation sensors (182, 184, 186, 188) for function monitoring.

[0286] 115. Device according to one of embodiments 79 to 114, wherein the deformation transmission element (102) is plate-like and each deformation-affected region (152, 154, 156, 158) carrying a deformation sensor (172, 174, 176, 178) is formed by a cross-sectional constriction of the deformation transmission element (102).

[0287] 116. The device according to embodiment 115, wherein the cross-sectional constriction of the deformation transmission element (102) is formed by a constriction of a surface extension of the deformation transmission element (102). 117. The device according to any one of embodiments 79 to 116, wherein the deformation sensors and the reference deformation sensors are designed as strain sensors, in particular strain gauges.

[0288] 118. Device according to one of embodiments 79 to 117, wherein the deformation sensors and the reference deformation sensors are designed as magnetostrictive or optical sensors.

[0289] 119. Device according to the preamble of embodiment 40 or according to one of embodiments 40 to 118, wherein the holding arm (30) has a first deformation region (82) and a second deformation region (84) between the first end (32) and the second end (34), which, when a force (Fx) acts parallel to the direction of travel (24) in the longitudinal center plane (18) of the holding arm (30), each experience deformations which differ from the deformations when a force (F z ) differentiate.

[0290] 120. Device according to embodiment 119, wherein the first and the second deformation region (82, 84) are deformed by a force (F y ) each experience deformations which differ from the deformations caused by a force F acting in the longitudinal center plane (18) parallel and / or transverse to the direction of travel (24) x , F2).

[0291] 121. Device according to embodiment 119 or 120, wherein the first and second deformation regions (82, 84) are arranged successively in the direction of extension of the holding arm (30).

[0292] 122. Device according to one of embodiments 40 to 121, wherein each deformation sensor (172, 174, 176, 178) is connected to the associated reference deformation sensor (182, 184, 186, 188) in a Wheatstone bridge (212, 214, 216, 218). 123. Device according to one of embodiments 40 to 122, wherein the evaluation unit (230) has a processor (234) which converts the values ​​corresponding to the deformations in the deformation-affected regions (152, 154, 156, 158) into the corresponding values ​​(WFx, WFY, WFZ) of three forces (F) acting transversely, in particular perpendicularly, to one another in spatial directions, using transformation values ​​determined and stored in a memory (236) by calibration. x , F y , F2) to the coupling element (40).

[0293] 124. Device according to one of the embodiments 40 to 122, wherein two of the forces (Fx, Fz) run parallel to, in particular in, the longitudinal center plane (18) of the holding arm (30) but transversely, in particular perpendicularly, to each other and that the third force (F y ) extends transversely, in particular perpendicularly, to the longitudinal center plane (18) of the holding arm (30).

[0294] 125. Device according to embodiment 123 or 124, wherein transformation values ​​for force combinations acting on the coupling element (40) in different octants are stored in the memory (236).

[0295] 126. Device according to one of embodiments 40 to 125, wherein the evaluation unit (230) records values ​​from deformation sensors (172, 174, 176, 178) and in particular reference deformation sensors (182, 184, 186, 188) to determine the deformations.

[0296] 127. Device according to embodiment 126, wherein the evaluation unit (230) records values ​​from at least one temperature sensor (252, 254, 256, 258) for functional testing of the reference deformation sensors (182, 184, 186, 188).

[0297] 128. Device according to embodiment 127, wherein the evaluation unit (230) records values ​​from a temperature sensor assigned to the respective reference deformation sensor. 129. Device according to one of embodiments 40 to 128, wherein the holding arm (30) carries the coupling element (40) at its second end (34).

[0298] 130. Device according to embodiment 129, wherein the holding arm (30) and the coupling element (40) form a continuous part.

[0299] 131. Device according to embodiment 129 or 130, wherein the holding arm (30) is designed as a ball neck and carries the coupling element (40) comprising a coupling ball (43) at the second end (34).

[0300] 132. Device according to one of embodiments 40 to 131, wherein the holding arm (30') comprises a receiving body (31') which is designed to releasably receive the coupling element (40').

[0301] 133. Device according to embodiment 132, wherein the receiving body (31') has an insertion receptacle (33') which is accessible through an insertion opening (35').

[0302] 134. Device according to embodiment 132 or 133, wherein the coupling element (40') comprises a support arm (42').

[0303] 135. Device according to one of embodiments 132 to 134, wherein the support arm (42') can be inserted into the insertion receptacle (33') with an insertion section (45') and can be fixed therein.

[0304] 136. Device according to one of embodiments 132 to 135, wherein the support arm (42') carries a coupling ball (43).

[0305] 137. Device according to embodiment 135 or 136, wherein the insertion section (45') is received transversely in an insertion direction (E) in a form-fitting manner in the insertion receptacle (33') and is fixed in the functional state in the insertion direction by a form-fitting body (41). 138. Device according to the preamble of embodiment 40 or according to one of embodiments 40 to 137, wherein the holding arm (30) is provided with at least three deformation sensors (172, 174, 176, 178) which react in particular in different ways to three forces acting on the coupling element (40) in spatial directions running transversely to one another, and in that the at least three deformation sensors (172, 174, 176, 178) supply sensor values ​​(M) from which at least one force component acting on the coupling element (40) is determined by means of an evaluation unit (270).

[0306] 139. Device according to one of embodiments 40 to 138, wherein the (230) comprises at least one of the values ​​(WF X , WF y , WFz) is determined from the force component running in the evaluation unit spatial directions (x, y, z).

[0307] 140. Device according to one of embodiments 40 to 139, wherein the evaluation unit (270) determines the value (WFz) of its force component running in the direction of gravity (Z).

[0308] 141. Device according to one of embodiments 40 to 140, wherein the evaluation unit (230) determines the value (F x ) of its force component running in the direction of travel of the motor vehicle (10).

[0309] 142. Device according to one of embodiments 40 to 141, wherein the evaluation unit (230) determines the value (F y ) of its force component extending transversely, in particular perpendicularly, to a vertical longitudinal center plane (18).

[0310] Further features and advantages of the inventive solution are the subject of the following description and the drawings of some exemplary embodiments.

[0311] Fig. 1 is a side view, partially broken away at the rear, of a motor vehicle body according to a first embodiment of a device according to the invention for coupling a trailer;

[0312] Fig. 2 is a rear view of the motor vehicle body looking in the direction of arrow X in Fig. 1;

[0313] Fig. 3 is a view of the first embodiment of the device for coupling a trailer or a load carrier unit in its working position according to Fig. 2;

[0314] Fig. 4 is a representation of the first embodiment of the device for coupling a trailer or a load carrier unit in a rest position R;

[0315] Fig. 5 is a side view of the holding arm of the first embodiment showing the loading of the coupling element with a force F x ;

[0316] Fig. 6 is a plan view of the support arm looking in the direction of arrow D in Fig. 5;

[0317] Fig. 7 a side view of the holding arm when a force F is applied z ;

[0318] Fig. 8 is a plan view of the holding arm according to Fig. 6 when the force F is applied z ;

[0319] Fig. 9 a side view of a holding arm under the action of a force F y ;

[0320] Fig. 10 a plan view similar to Fig. 6 under the action of force F y ; Fig. 11 is a section along line 11-11 in Fig. 5;

[0321] Fig. 12 an enlarged plan view of the holding arm with the deformation transmission element under the action of force F x according to Fig.

[0322] 5 and 6;

[0323] Fig. 13 a plan view corresponding to Fig. 12 under the action of force F z according to Fig. 7 and 8;

[0324] Fig. 14 a plan view similar to Fig. 12 under the action of a force F y according to Fig.9 and 10;

[0325] Fig. 15 is an enlarged plan view of the deformation transmission element according to a first embodiment with the deformation sensors and reference deformation sensors arranged thereon;

[0326] Fig. 16 is a diagram of a Wheatstone bridge for connecting a first deformation sensor and a first reference deformation sensor;

[0327] Fig. 17 is a representation of the Wheatstone bridge corresponding to Fig. 16 for connecting a second deformation sensor and a second reference deformation sensor;

[0328] Fig. 18 is a representation of a Wheatstone bridge corresponding to Fig. 16 for connecting a third deformation sensor and a third reference deformation sensor;

[0329] Fig. 19 shows a representation of a Wheatstone bridge according to Fig. 16 for connecting a fourth deformation sensor and a fourth reference deformation sensor; Fig. 20 shows a representation of an evaluation circuit for processing the voltages measured in the Wheatstone bridges according to Fig. 16 to Fig. 19;

[0330] Fig. 21 shows a representation of a coupling element 40 and the forces acting on the coupling element 40 as determined by the evaluation circuit;

[0331] Fig. 22 is a side view of the first embodiment showing a circuit board carrying the evaluation circuit;

[0332] Fig. 23 is a side view of a unit comprising a circuit board carrying the evaluation circuit and the deformation transmission element with deformation sensors and reference deformation sensors;

[0333] Fig. 24 is a representation of a second embodiment of a device according to the invention with a reversed arrangement of the unit comprising the deformation transmission element, the strain sensors, the reference strain sensors and the evaluation unit;

[0334] Fig. 25 is a representation of a third embodiment of a device according to the invention similar to Fig. 23 showing the additional temperature sensors arranged on the circuit board;

[0335] Fig. 26 is a representation of a fourth embodiment of a device according to the invention, showing the deformation transmission element and additional temperature sensors arranged thereon; Fig. 27 is a representation of the evaluation unit according to the third or fourth embodiment, similar to Fig. 20;

[0336] Fig. 28 is a side view similar to Fig. 1 of a fifth embodiment of a device according to the invention;

[0337] Fig. 29 is a perspective view of the fifth embodiment of the device according to the invention in working position;

[0338] Fig. 30 is a view of the fifth embodiment looking in the direction of arrow X' in Fig. 28 in the working position;

[0339] Fig. 31 is a section along line 31-31 in Fig. 30;

[0340] Fig. 32 is a section along line 32-32 in Fig. 30;

[0341] Fig. 33 a section similar to Fig. 31 of the embodiment in the rest position;

[0342] Fig. 34 is a perspective view of the fifth embodiment in the rest position looking in the direction of arrow Y' in Fig. 33;

[0343] Fig. 35 a side view of the holding arm of the fifth embodiment showing the loading of the coupling element with a force F x ;

[0344] Fig. 36 is a plan view of the support arm looking in the direction of arrow D' in Fig. 35;

[0345] Fig. 37 a side view of the holding arm of the fifth embodiment under the action of a force F z ; Fig. 38 a plan view of the holding arm according to Fig. 36 under the action of force F z ;

[0346] Fig. 39 a side view of a holding arm of the fifth embodiment under the action of a force F y ;

[0347] Fig. 40 a plan view similar to Fig. 36 under the action of force F y ;

[0348] Fig. 41 shows a representation of a first possibility of mathematically linking the values ​​of the force components with the sensor values;

[0349] Fig. 42 is a schematic representation of the procedure for calibrating a holding arm;

[0350] Fig. 43 shows a representation of a second possibility of mathematically linking the values ​​of the force components with the sensor values;

[0351] Fig. 44 shows a representation of a calibration based on force components in octants with the coupling element as the center point;

[0352] Fig. 45 a schematic representation of an evaluation unit and its interaction with other components;

[0353] Fig. 46 is an exemplary representation of a motor vehicle with a trailer;

[0354] Fig. 47 is a view of a motor vehicle with a bicycle carrier;

[0355] Fig. 48 is a representation of deformation values ​​measured on a trailer with two deformation sensors each, arranged on opposite sides of a longitudinal center plane, per deformation area;

[0356] Fig. 49 shows a representation of deformation values ​​measured on a bicycle carrier with two deformation sensors each, arranged on opposite sides of a longitudinal center plane, per deformation area;

[0357] Fig. 50 is a representation of averaged deformation values ​​measured on a trailer per deformation area;

[0358] Fig. 51 shows a representation of averaged deformation values ​​per deformation area measured on a bicycle carrier;

[0359] Fig. 52 shows a representation of time-resolved deformation values ​​for two deformation sensors each, arranged on opposite sides of a longitudinal center plane, per deformation area with an impulse-like effect of the trailer and

[0360] Fig. 53 shows a representation of time-resolved deformation values ​​recorded for two deformation sensors each, arranged on opposite sides of a longitudinal center plane, per deformation area during a swaying movement of the trailer.

[0361] A motor vehicle, designated as a whole by 10, comprises a motor vehicle body 12 which is provided at a rear region 14, namely near a vehicle floor 16, with a support unit 20 which has, for example, a cross member 22 which is connected to the rear region 14 near the vehicle floor 16.

[0362] The connection between the cross member 22 and the rear area 14 can be made, for example, via mounting flanges adjacent to the rear area 14 or, for example, by side members 26 extending in a vehicle longitudinal direction 24, which abut vehicle body sections 28 also extending in the vehicle longitudinal direction 24.

[0363] A holding arm, designated as a whole by 30, in particular a ball neck, is connected to the carrier unit 20 in that a first end 32 of the holding arm 30 is held either directly or via a bearing unit 36 ​​on the carrier unit 20, preferably on the cross member 22.

[0364] The holding arm 30 carries a coupling element 40 at a second end 34 opposite the first end 32, which is provided, for example, for attaching a trailer or for fixing a load carrier unit.

[0365] For example, such a coupling element 40 is designed as a coupling ball 43, which allows a common connection to a towing ball coupling of a trailer.

[0366] However, the coupling ball 43 also allows for easy mounting of a load carrier unit, since commonly used load carrier units are also designed in such a way that they can be mounted on a coupling ball and, if necessary, additionally supported on the holding arm 30.

[0367] The coupling element 40 is seated, for example, on a support 42 which is connected to the second end region 34 of the holding arm 30 and extends from a side of the support 42 facing away from a roadway 44 in the direction of a central axis 46 which, when the roadway 44 is horizontal, runs approximately vertically and which, in the case of the coupling ball 43, runs through a ball center point 48.

[0368] To improve the aesthetic effect, the cross member 22 is preferably arranged under a rear bumper unit 50 of the motor vehicle body 12, wherein the bumper unit 50, for example, conceals the cross member 22 and the first end 32 of the support arm 30. In particular in the illustrated embodiment, the support arm 30 carries the coupling element 40 designed as a coupling ball, wherein the support arm 30, as shown in particular in Figs. 1 to 3, extends from the pivot bearing unit 36, to which the support arm 30 is connected at its first end region 32, wherein, for example, a pivot bearing body 52 of the pivot bearing unit 36 ​​is formed on the first end region 32.

[0369] The pivot bearing body 52 of the pivot bearing unit 36 ​​is mounted on a pivot bearing receptacle 56 so as to be pivotable about a pivot axis 54 which runs in particular obliquely to a vertical longitudinal center plane 18 of the vehicle, which on the one hand guides the pivot bearing body 52 so as to be rotatable about the pivot axis 54 and on the other hand comprises a locking unit (not shown in the drawing) which, in the working position and the rest position, enables the holding arm 30 to be fixed in a rotationally fixed manner with respect to pivoting movements about the pivot axis 54.

[0370] The pivot bearing holder 56 is then in turn firmly connected to the cross member 22 via a pivot bearing base 58.

[0371] As shown in Fig. 1 to 4, the holding arm 30 in this embodiment can be pivoted from a working position A, shown in Fig. 1 to 3, in which the coupling element designed as a coupling ball 40 is positioned such that it is located behind the bumper unit 50 on a side facing away from a roadway 44, into a rest position R, shown in Fig. 4, in which the coupling element 40 is arranged facing the roadway 44.

[0372] The coupling element 40 can be moved under a lower edge 51 of the bumper unit 50.

[0373] In particular, the holding arm 30 extends in the working position A essentially in the vertical longitudinal center plane 18 of the vehicle, which intersects the coupling element 40 in the middle if the latter is designed as a coupling ball, so that in the working position A a vertical ball center axis 48 lies in the longitudinal center plane 18.

[0374] Starting from the first end region 32, the holding arm 30 in the illustrated embodiment extends with a first curved piece 62 to an intermediate piece 64, which extends to an annular body 66, to which a second curved piece 68 is connected on a side opposite the intermediate piece 64 and the curved piece 62, which in turn carries the coupling element 40 designed as a coupling ball, wherein the ball extension 42 is also provided between the coupling element 40 designed as a coupling ball and the second curved piece 148.

[0375] The second curved piece 68 then forms the end region 34 of the holding arm 30, which then carries, for example, the ball attachment 42, to which the coupling element 40 designed as a coupling ball is connected.

[0376] As shown in particular in Figs. 4 and 5, for easy mounting of a contact unit on the holding arm 30, the annular body 66 is arranged adjacent to the intermediate piece 64, which annular body 66 encloses a passage 72 in which a contact unit can be mounted.

[0377] Preferably, the annular body 66 is arranged in such a way that a transition into the second curved piece 68 takes place following the annular body 66.

[0378] A holding arm 30 designed in this way is approximately U-shaped by the first curved piece 62, the intermediate piece 64 and the second curved piece 68, and in the working position A, in which loads on the coupling element 40 occur and are to be detected, is aligned such that the forces acting on the coupling element 40, in particular the ball center 46, are transmitted via the approximately U-shaped design of the holding arm 30 to the pivot bearing body 52 of the pivot bearing unit 36, wherein the pivot axis 54 represents a center of force absorption by the pivot bearing unit 36.

[0379] The forces acting on the coupling element 40 are, as shown in Figs. 1 to 8, transmitted by the holding arm 30 to the bearing unit 36 ​​and from there to the carrier unit 20, which then transmits the forces into the rear area 14 of the motor vehicle body 12, wherein different areas of the holding arm 30 are used to detect the forces acting on the coupling element 40.

[0380] In the exemplary embodiment described above, a first deformation region 82 of the holding arm 30 is used as an example, which comprises a section of the intermediate piece 64 and the annular body 66, and a second deformation region of the holding arm 30 is used, which comprises a section of the annular body 66 and the second curved piece 68.

[0381] Furthermore, in this embodiment, it is assumed that the ring region 66 has a high stability with respect to bending forces running in the longitudinal center plane 18 and also transversely thereto, and in particular is sufficiently stiff also against tensile loads.

[0382] For example, the force F shown in Fig. 5 and 6 x , which runs in the longitudinal center plane 18, in particular in the longitudinal direction of the vehicle and is directed, for example, perpendicular to the center axis 46 and away from the pivot bearing body 52, means that in the deformation areas 82 and 84, on the one hand, tensile forces ZX1 and ZX2 (Fig. 6) occur and / or also bending forces BX1 and BX2 (Fig. 5), which can also overlap, these forces acting in the direction of the longitudinal center plane 18, in particular in the longitudinal center plane 18, of the holding arm 30.

[0383] Furthermore, in the deformation areas 82 and 84, as shown in Figs. 7 and 8, when the coupling element 40 is loaded with a force F acting in the vertical direction, in particular in the direction of gravity, z , which, for example, also acts in the direction of the central axis 46 when the vehicle is standing on an approximately horizontal plane, essentially bending forces BZ1 and BZ2 in the deformation regions 82 and 84, these forces acting in a direction parallel to the longitudinal center plane 18, in particular in the longitudinal center plane 18, of the holding arm 30, which thus have opposing effects on opposite sides with respect to a so-called length-invariable neutral fiber NF.

[0384] Preferably, the deformation regions 82 and 84 are arranged on the holding arm 30 and / or the holding arm 30 is designed in the deformation regions 82, 84 in such a way that deformations of varying degrees occur in the latter when a force Fz acts in the direction of gravity or opposite thereto.

[0385] It is particularly useful - as explained in detail below - if the force F acting in the vertical direction z significantly lower deformations are generated in the deformation area 84 than in the deformation area 82 and when a combined force with approximately equal force components F x + F z the deformations in both deformation areas 82 and 84 are approximately similar in size.

[0386] For this reason, the deformation area 82 is strongly sensitive to the support load and the deformation area 82 is weakly sensitive to the support load

[0387] In addition, a force F acting on the coupling element 40 y , which is directed perpendicular to the longitudinal center plane 18 and perpendicular to the center axis 46, as shown in Fig. 9 and 10, to bending forces BY1 and BY2 acting opposite to each other on both sides of the longitudinal center plane 18 but on different sides thereof.

[0388] To detect these tensile forces ZX1 and ZX2 as well as the bending forces BX1 and BX2, BZ1 and BZ2 as well as BY1 and BY2, a force detection module designated as a whole by 100 is arranged on the holding arm 30.This force detection module 100 comprises a deformation transmission element 102 which is rigidly connected to the holding arm 30 at three fastening areas 104, 106 and 108, wherein the fastening area 104 is located on a side facing the first end 32 and is rigidly connected to a projection 114 of the holding arm 30, for example sitting on the central piece 64, the fastening area 106 is arranged approximately centrally between the fastening areas 104 and 108 and is connected, for example, to a holding projection 116 sitting on the annular body 66, in particular centrally thereof, and the fastening area 108 is connected to a projection 118 of the holding arm 30 arranged on the curved piece 68, for example in a central area of ​​the curved piece 68 between the annular body 66 and the end 34.

[0389] The connection between the respective connecting elements 114, 116 and 118 of the holding arm 30 is rigid and free of play, preferably by welding or gluing, which does not allow any elasticity of movement between the deformation transmission element 102 and the connecting elements 114, 116 and 118.

[0390] Preferably, the connecting elements 114, 116 and 118 are also rigidly connected to the holding arm, in particular formed thereon.

[0391] Preferably, as shown in Fig. 11 using the example of the projection 114, the connecting elements 114, 116, and 118 of the holding arm 30 are designed such that they have a base region 122 extending from the holding arm 30 and forming a fixing pin 124 that penetrates an opening 126 arranged in the respective fastening region, in this case the fastening region 104 of the deformation transmission element 102. Preferably, the fixing pin 124 and the opening 126 are shaped such that they can be rigidly connected to one another by a weld seam 128.

[0392] Furthermore, the foot region 122 is preferably designed such that it has a shoulder 132 surrounding the fixing pin 124, on which shoulder the deformation transmission element 102 rests with a support surface 134 of the fastening region 104 surrounding the opening 126 and is thereby supported, for example, when the weld seam 128 is applied.

[0393] The deformation transmission element 102 is further designed such that it has deformation-resistant regions 144, 146 and 148, which in particular also comprise the fastening regions 104, and that deformation-affected regions 152, 154, 156, 158 are arranged between the deformation-resistant regions 144, 146, 148, wherein, for example, the deformation-affected regions 152 and 154 are located between the deformation-resistant regions 144 and 146, which are preferably arranged at the same distance from the longitudinal center plane 18, but on opposite sides thereof, and the deformation-affected regions 156 and 158 are located between the deformation-resistant regions 146 and 148, which are also arranged on opposite sides of the longitudinal center plane 18, but preferably at the same distance from it.

[0394] Preferably, the deformation-affected regions 152 to 158 are designed as deformation concentration regions, i.e., in these deformation concentration regions 152, 154, 156, 158, a deformation acting on the deformation transmission element 102 has a significantly stronger effect than in the deformation-stiff regions 144, 146, and 148. The formation of such a deformation concentration region can be realized in the simplest case by the material in the deformation concentration regions 152 to 158 having a lower stiffness than in the deformation-stiff regions 144, 146, and 148.

[0395] Such a variation in stiffness can be achieved, for example, by changing the material in the area of ​​the deformation concentration regions 152, 154, 156, 158 or by changing the effective material cross-section.

[0396] In the illustrated embodiments according to Figs. 6, 8 and 10, the deformation concentration regions 152, 154, 156 and 158 are formed as narrow webs of a plate 162 forming the deformation transmission element 102, while the deformation-resistant regions 144, 146 and 148 are formed by broadly extending regions of the plate 162.

[0397] In summary, such a design of the deformation transmission element 102 has the consequence that a deformation of the deformation region 82 of the holding arm 30 leads to a relative movement of the connecting elements 114 and 116 rigidly connected to the holding arm 30, which is transmitted to the fastening regions 104 and 106 and from there to the deformation-resistant regions 144 and 146 of the deformation transmission element 102, wherein the deformation-resistant regions 144 and 146 of the deformation transmission element 102 experience essentially no deformation and thus transmit the entire deformations forming in the deformation region 82 to the deformation-affected regions 152 and 154, which, by also being designed as deformation concentration regions, concentrate the entire deformation forming between the connecting elements 114 and 116 in the deformation region 82. experience.This means that the deformation concentration areas 152 and 154 experience deformations due to the bending forces BX1 acting in the longitudinal center plane 18 as well as deformations due to the tensile forces ZX1 as well as the deformations caused by the forces BZ1 and BZ2, whereby since these deformations are all based on forces acting essentially in the longitudinal center plane 18, both deformation concentration areas 152 and 154 experience approximately the same deformation when the holding arm 30 is designed symmetrically to the longitudinal center plane 18.

[0398] This is different with the bending forces BY1 shown in Fig. 9 and 10, which act on different sides of the longitudinal center plane 18 in different directions, so that, for example, starting from the bending forces BY1 shown in Fig. 9 and 10, the deformation concentration region 152 experiences a deformation based on a compressive load, while the deformation concentration region 154 experiences a deformation based on a tensile load.

[0399] In an analogous manner, deformations of the deformation region 84 of the holding arm are transferred by the connecting elements 116 and 118 to the fastening regions 106 and 108, which are part of the deformation-resistant regions 146 and 148 and which thus transfer the deformations of the deformation region 84 to the deformation-affected regions 156 and 158, which are also designed as deformation concentration regions and thus experience the entire deformation of the deformation region 84.

[0400] This also results in the forces BX2, ZX2 and BZ2, which are all essentially effective in the longitudinal center plane 18, acting in the same way on the deformation concentration regions 156 and 158 when the holding arm 30 is designed symmetrically to the longitudinal center plane 18, while the forces BY2 lead to opposite deformations in the deformation regions 156 and 158, so that, for example, the deformation in the deformation concentration region 156 is based on a compressive load, while the deformation in the deformation concentration region 158 is based on a tensile load.

[0401] Because the deformation areas 82 and 84 of the holding arm when the coupling element 40 is loaded by the force F x experience a different deformation than when the coupling element 40 is loaded by the force F z, due to the different deformations of the deformation areas 82 and 84, it is possible to determine, based on the different deformations occurring in the deformation concentration areas 152 and 154 or 156 and 158, whether a force F x or a force F z acts on the coupling element 40, as explained in detail below.

[0402] For simplified explanation, it can be assumed, for example, that, as shown in Fig. 12, the deformations D152 in the deformation concentration region 152, the deformation D154 in the deformation concentration region 154, the deformation D156 in the deformation concentration region 156 and the deformation D158 in the deformation concentration region 158 are essentially the same size if the deformation regions 82 and 84 behave essentially in the same way under the occurring bending forces BX1 and BX2, combined with the occurring tensile forces ZX1 and ZX2.

[0403] Furthermore, the behavior of the deformations in the deformation areas 82 and 84 can change when the force F zchange so that, as exemplified in Fig. 13, the deformations D152 and D154 in the deformation concentration regions 152 and 154 can be significantly smaller than the deformations D156 and D158 in the deformation concentration regions 156 and 158.

[0404] The situation is different again when the force F y , as shown in Fig. 14. In this case, compression occurs in the deformation concentration regions 152 and 156 as deformation D152 and D156, while strain occurs in the deformation concentration regions 154 and 158 as deformation D154 and D158, respectively.

[0405] The compression-based deformations D152 and D156 can be the same or different and, in the same way, the strain-based deformations D154 and D158 can be the same or different.

[0406] To record the strains or compressions caused by forces Fx and / or F2 and / or F y In order to detect the strains and compressions that occur in the deformation concentration areas 152, 154, 156 and 158, as shown in Fig. 15, a deformation sensor 172, 174, 176 and 178 is arranged in each of the deformation concentration areas 152, 154, 156 and 158, with which it is possible to detect the strains and compressions in the respective deformation concentration areas 152, 154, 156 and 158 as deformations.

[0407] Since in the deformation concentration areas 152, 154, 156 and 158 not only expansions and compressions occur which are caused by the deformation areas 82 and 84 of the holding arm 30, but also expansions and compressions can occur which are caused by a temperature expansion of the material in the deformation concentration areas 152, 154, 156 and 158, reference deformation sensors 182, 184, 186 and 188 are assigned to the deformation sensors 172, 174, 176 and 178, which are arranged on load-free reference areas 192, 194, 196 and 198 of the deformation transmission element 102, wherein these load-free reference areas 192, 194, 196 and 198 are preferably designed as close as possible to the Deformation concentration regions 152, 154, 156, 158 are formed by tongues 202, 204, 206 and 208 which extend from, for example, the deformation-free regions 144 and 148 substantially parallel to the deformation concentration regions 152, 154,156 and 158, however, extend without contact to these and also to the deformation-free region 146, wherein preferably the load-free reference regions 192, 194, 196 and 198 in the region in which they carry the reference deformation sensors 182, 184, 186 and 188 have substantially the same material cross-section with the same material cross-sectional shape as the deformation concentration regions 152, 154, 156 and 158, and furthermore, the reference deformation sensors 182, 184, 186, 188 are preferably also identical to the deformation sensors 172, 174, 176 and 178.

[0408] For electronic detection of the deformations in the form of strains and compressions in the deformation concentration regions 152, 154, 156 and 158, the deformation sensors 172, 174, 176 and 178 arranged therein are each arranged in Wheatstone bridges 212, 214, 216 and 218, wherein the respective Wheatstone bridges 212, 214, 216 and 218 are located between supply terminals V+ and V-, as shown in Figs. 16 to 19.

[0409] Furthermore, in the Wheatstone bridges 212, 214, 216, 218, the deformation sensors 172, 174, 176 and 178 are connected in series between the supply terminals V+ and V- with the reference deformation sensors 182, 184, 186 and 188 respectively assigned to them, and resistors 222 and 224 are connected in parallel to this series connection of the deformation sensors 172, 174, 176 and 178 with the reference deformation sensors 182, 184, 186 and 188 to form the Wheatstone bridges 212, 214, 216, 218, wherein the resistors 222 and 224 have the same fixed values.

[0410] Thus, in the respective Wheatstone bridges 212, 214, 216 and 218, a voltage U can be tapped at the center taps between the deformation sensors 172, 174, 176 and 178 and the reference deformation sensors 182, 184, 186 and 188 and the center taps between the resistors 222 and 224, which voltage U essentially corresponds to the deformations, i.e. the strains and compressions, that occur in the deformation concentration regions 152, 154, 156 and 158, wherein by providing the reference deformation sensors 182, 184, 186, 188, temperature effects and in particular also temperature strains in the deformation concentration regions 152, 154, 156 and 158 are largely compensated, which is particularly is possible if the reference deformation sensors 182, 184, 186 and 188 are identical sensors to the deformation sensors 172, 174, 176 and 178.

[0411] The voltages UD152, UD154, UD156 and UD158 tapped in the Wheatstone bridges 212, 214, 216, 218 and corresponding to the deformations in the deformation concentration regions 152, 154, 156 and 158 are fed to an A / D converter 232 of an evaluation unit 230 comprising the latter, as shown in Fig. 20.

[0412] The A / D converter 232 determines digital deformation values ​​D152, D154, D156, D156, D158 from the sensor values ​​UD152, UD154, UD156 and UD158, which are transmitted to a load analysis stage 233, which will be described in more detail below.

[0413] The deformation values ​​D153, D154, D156 and D158 are also transmitted, in particular parallel to the load analysis stage 233, to a force analysis stage 234, which, by means of program code and a processor, from the digital deformation values ​​D152, D154, D156 and D158 and by comparing them with transformation values ​​for the deformation values ​​D152, D154, D156 and D158 determined during a calibration process and stored in a memory 236, for example at corresponding outputs values ​​WF X , WF Z and WF y which corresponds to the forces F x , F z and F y are assigned.

[0414] In the simplest case, a transformation matrix T valid for all spatial directions is stored in the memory 236, with which the digital deformation values ​​D152, D154, D156 and D158 can be converted into values ​​WF X and WF Z and WF yfor the forces acting on the coupling element 40. An improvement in the quality of the values ​​WF X , WF Z and WF y can be achieved if the calibration for the value pairs WFx, WFz and WF in each of the octants I to VIII arranged around the pendant element 40 according to Fig. 21 y so that it is also possible to establish a non-linear correlation between the forces Fz, F acting on the coupling element 40 z , F y and the digital deformation values ​​D152, D154, D156 and D158 into the calibration and thus transformation of these deformation values ​​D152, D154, D156 and D158 into the values ​​WFx, WF Z and WF y for the forces acting on the coupling element 40.

[0415] This increases the accuracy of the determined values ​​WFx, WF Z and WF y significantly improved.

[0416] With regard to the arrangement of the evaluation unit 230, comprising in particular the A / D converter 232, the load analysis stage 233, the force analysis stage 234 and the memory 236, a wide variety of possibilities are conceivable.

[0417] For example, it is conceivable to arrange the evaluation unit 230 directly on the deformation transmission element 102.

[0418] However, it is particularly advantageous if the evaluation unit 230 is arranged on a circuit board 240 which is coupled to the deformation transmission element 102 but arranged separately from it.

[0419] Not only the evaluation unit 230, but also the resistors 222 and 224 of the respective Wheatstone bridges 212, 214, 216 and 218 can then be arranged on this circuit board 240.

[0420] A particularly advantageous embodiment provides that the deformation sensors 172, 174, 176 and 178 as well as the reference deformation sensors 182, 184, 186 and 188 are arranged on one side of the deformation transmission element 102, specifically on a side that faces the circuit board 240, while on the circuit board 240 the evaluation unit 230, in particular with the A / D converter 232, the load analysis stage 233, the force analysis stage 234 and the memory 236, are arranged on a side that also faces the deformation transmission element 102.

[0421] Preferably, the deformation transmission element 102 and the circuit board 240 are also enclosed or cast in an encapsulating material 242, so that the deformation transmission element 102, the circuit board 240 and the encapsulating material 242 form a common unit 244 (Fig. 23).

[0422] This unit 244 can be mounted on the connecting elements 114, 116 and 118 either in such a way that the circuit board 240 lies on a side of the deformation transmission element 102 facing away from the holding arm 30, as shown, for example, in Fig. 22.

[0423] However, in a second embodiment, it is also possible to arrange the unit 244 such that the circuit board 240 lies on a side of the deformation transmission element facing the holding arm 30, as shown, for example, in Fig. 24.

[0424] In a third embodiment, to safeguard the functions of the reference deformation sensors 182, 184, 186 and 188, for example, a separate temperature sensor 252, 254, 256 and 258 is assigned to each of the reference deformation sensors 182, 184, 186, 188.

[0425] The separate temperature sensors 252, 254, 256, 258 can be arranged either on the circuit board 240, as shown in Fig. 25, or, as shown in a fourth embodiment in Fig. 26, on the deformation transmission element 102. Such an additional temperature sensor 252, 254, 256, 258 opens up the possibility of performing an additional temperature measurement in order to check whether the reference deformation sensors 182, 184, 186 and 188 are fully functional or whether incorrect measurements with regard to the voltages UD152, UD154, UD156 and UD158 could be present due to functional limitations or functional failures of these reference deformation sensors 182, 184, 186, 188.

[0426] The voltages UD252, UD254, UD256 and UD258 measured, for example, at these temperature sensors 252, 254, 256 and 258 are also fed to the A / D converter 232, both in the case of the arrangement on the circuit board 240 (Fig. 25) and in the case of the arrangement on the deformation transmission element 102 (Fig. 26), as shown in Fig. 27, and converted by the latter into the values ​​T252, T254, T256, T258 and fed to the load analysis stage 233 and / or the force analysis stage 234 and then checked by the load analysis stage 233 and / or the force analysis stage 234 before carrying out the evaluation of the corresponding digital deformation values ​​D152, D154, D156, D158.

[0427] In a fifth embodiment, a holding arm designated as a whole by 30' is connected to the carrier unit 20 in that the first end 32' of the holding arm 30' is held either directly or via a bearing unit 36' on the carrier unit 20, preferably on the cross member 22.

[0428] The holding arm 30' comprises a receiving body 31 and the first end 32' and the second end 34' and is designed to receive a coupling element 40', which is provided, for example, for attaching a trailer or for fixing a load carrier unit.

[0429] For example, such a coupling element 40' is designed as a coupling ball 43' held on a support arm 42', which allows a common connection to a towing ball coupling of a trailer, wherein the support arm 42' can be inserted with an insertion section 45 into an insertion receptacle 33' of the receiving body 31' through an insertion opening 35 which is rearward in the working position A, as seen in the direction of travel, into the receiving body 31 and can be fixed therein.

[0430] The coupling element 40' is connected, for example, by means of the support arm 42' to the holding arm 30' in such a way that the coupling ball 43 extends from a side of the support arm 42' facing away from a roadway 44 in the direction of a central axis 46 which, when the roadway 44 is horizontal, runs approximately vertically and which, in the case of the coupling ball 43', runs through a ball center point 48.

[0431] In particular, the insertion receptacle 33' is designed such that it receives the insertion section 45 transversely to an insertion direction E in a form-fitting and releasable manner and provides a safeguard against movement in the insertion direction ER by means of a form-locking element 41.

[0432] In particular, the insertion section 45 of the support arm 42' is releasably fixed in the receiving body 31 by a fixing bolt 41 extending transversely to the vehicle longitudinal center plane 18 and passing through both the receiving body 31 and the support arm 42'.

[0433] However, a coupling element 40' designed in this way also allows for easy assembly of a load carrier unit, since commonly used load carrier units are also designed in such a way that they can be mounted on the coupling ball 43 and, if necessary, additionally supported on the holding arm 30.

[0434] Alternatively, however, only a carrier arm 42 held on the load carrier unit with an insertion section 45 suitable for insertion into the insertion receptacle 33' can be used as the coupling element 40'.

[0435] To improve the aesthetic effect, the cross member 22 is preferably arranged under a rear bumper unit 50 of the motor vehicle body 12, wherein the bumper unit 50, for example, conceals the cross member 22 and a part of the first end 32' of the support arm 30'.

[0436] The holding arm 30' carries, in particular in the fifth exemplary embodiment shown, the coupling element 40' comprising the coupling ball 43 through the plug-in section 45 inserted into the plug-in receptacle 33', wherein the holding arm 30', as shown in particular in Figs. 28 to 32, extends from the pivot bearing unit 36', to which the holding arm 30' is connected at its first end region 32', wherein, for example, a pivot bearing body 52' of the pivot bearing unit 36' is formed on the first end region 32'.

[0437] In the fifth exemplary embodiment, the pivot bearing body 52' of the pivot bearing unit 36' is mounted on a pivot bearing receptacle 56' so as to be pivotable about a pivot axis 54' running in particular transversely to the vertical longitudinal center plane 18 of the vehicle, which on the one hand guides the pivot bearing body 52' so as to be rotatable about the pivot axis 54' and on the other hand comprises a locking mechanism which, in the working position A and the rest position R, enables the holding arm 30' to be fixed in a rotationally fixed manner with respect to pivoting movements about the pivot axis 54'.

[0438] With regard to the design of the pivot bearing unit 36' and the respective locking of the pivot bearing body 52' relative to the pivot bearing holder 56', reference is made in full to DE 10 2016 107 302 A1.

[0439] In particular, for locking the pivot bearing body 52' in the working position A, a stop element 59' shown in Fig. 31 is provided, which extends through an opening in the holding arm 30' and is supported on an end of the insertion section 45 of the support arm 42', which is inserted into the insertion receptacle 33' and is arranged remote from the insertion opening 35', and thereby blocks a pivoting movement of the holding arm 30' with the receiving body 31' about the pivot axis 54' while simultaneously interacting with a stop unit 60' (Fig. 32), comprising stop elements arranged on the pivot bearing body 52' and the pivot bearing receptacle 56'.

[0440] In addition, the pivot bearing body 52' is locked in the rest position R by a locking device 61, shown in Fig. 33.

[0441] The pivot bearing holder 56' is then in turn firmly connected to the cross member 22 via a pivot bearing base 58'.

[0442] As shown in Fig. 28 to 34, the holding arm 30' in this fifth embodiment can be pivoted from a working position A, shown in Fig. 28 to 32, in which the coupling element 40' having the coupling ball 43 is positioned such that it is located behind the bumper unit 50 on a side facing away from a roadway 44, into a rest position R, shown in Fig. 33 and 34, in which, when the coupling element 40' is dismantled, an insertion opening 35 of the insertion receptacle 33 is arranged facing the roadway 44.

[0443] In particular, the holding arm 30' extends in the working position A essentially in the vertical longitudinal center plane 18 of the vehicle, which intersects the coupling element 40' in the middle if the latter is designed as a coupling ball 43 provided with the support arm 42, so that in the working position A a vertical ball center axis 48 lies in the longitudinal center plane 18.

[0444] Starting from the first end region 32', the receiving body 31' of the holding arm 30' in the illustrated embodiment extends with an extension piece 62' to an intermediate piece 64', which extends to an intermediate body 66, to which an end piece 68 is connected on a side opposite the intermediate piece 64 and the extension piece 62, beyond which the coupling element 40' extends with the support arm 42 arranged between the coupling ball 43 and the end piece 68. The end piece 68 forms the end region 34' of the holding arm 30', wherein the holding arm 30' with the plug-in receptacle 33' absorbs the forces transmitted to it by the plug-in section 45 of the support arm 42'.

[0445] A holding arm 30' designed in this way and absorbing the forces transmitted by the insertion section 45 is, as shown in Fig. 35 to 40, approximately rectilinear by the extension piece 62', the intermediate piece 64' of the intermediate body 66 and the end piece 68, and in the working position A, in which loads on the coupling element 40' occur and are to be detected, is aligned such that the forces acting on the coupling element 40', in particular the ball center 46, are transmitted via the holding arm 30' to the pivot bearing body 52' of the pivot bearing unit 36', wherein the pivot axis 54' represents a center of force absorption by the pivot bearing unit 36'.

[0446] The forces acting on the coupling element 40 are transmitted, as shown in Figs. 28 to 32, by the holding arm 30' to the bearing unit 36' and from there to the carrier unit 20, which then introduces these forces into the rear area 14 of the motor vehicle body 12, wherein different areas of the holding arm 30' are used to detect the forces acting on the coupling element 40.

[0447] In the exemplary embodiment described above, a first deformation region 82 of the holding arm 30' is used as an example, which is formed, for example, by a transition region from the intermediate piece 64' into the intermediate body 66', and a second deformation region of the holding arm 30' is used, which is formed by a transition region of the intermediate body 66' into the end piece 68'.

[0448] Furthermore, this exemplary embodiment assumes that the intermediate body 66' exhibits high stability against bending forces running in the longitudinal center plane 18 and also transversely thereto, and in particular, reacts primarily to tensile loads. The first and second deformation regions 82, 84 are formed, for example, by a region that is specifically designed, for example, by material weakening or material reinforcement. In the simplest case, the material weakening can be caused by an introduced cross-sectional variation.

[0449] 35 and 36, which is directed in the longitudinal center plane 18 and perpendicular to the center axis 46 and away from the pivot bearing body 52, leads to tensile forces ZX1 and ZX2 (Fig. 36) occurring in the deformation regions 82 and 84 on the one hand and, on the other hand, at least in the case of the coupling ball 43' projecting from the support arm 42' in the operating position on a side facing away from the roadway 44, also bending forces BX1 and BX2 (Fig. 35), which are superimposed on these tensile loads ZX1 and ZX2, these forces acting in the direction of the longitudinal center plane 18, in particular in the longitudinal center plane 18, of the holding arm 30'.

[0450] Furthermore, in the deformation areas 82 and 84, as shown in Fig. 37 and 38, when the coupling element 40 is loaded with a force F z, which acts in the direction of the central axis 46, in the deformation regions 82 and 84 essentially bending forces BZ1 and BZ2, these forces acting in the direction of the longitudinal center plane 18, in particular in the longitudinal center plane 18, of the holding arm 30, which thus have opposing effects on opposite sides with respect to a so-called length-invariable neutral fiber NF.

[0451] In addition, a force F acting on the coupling element 40 y, which is directed perpendicular to the longitudinal center plane 18 and perpendicular to the center axis 46, as shown in Figs. 39 and 40, to bending forces BY1 and BY2 acting in opposite directions on both sides of the longitudinal center plane 18, but on different sides of the same. In particular, the deformation regions 82 and 84 are designed such that they react to the tensile forces Z and the bending forces B with deformations of different magnitudes, for example, the deformation region 82 is highly sensitive to the support load and the deformation region 84 is weakly sensitive to the support load.

[0452] To detect these tensile forces ZX1 and ZX2 as well as the bending forces BX1 and BX2, BZ1 and BZ2 as well as BY1 and BY2, a force detection module designated as a whole by 100 is arranged on the holding arm 30'.

[0453] This force detection module 100 comprises a deformation transmission element 102 which is rigidly connected to the holding arm 30' at three fastening areas 104, 106 and 108, wherein the fastening area 104 is located on a side facing the first end 32 and is rigidly connected to a projection 114 of the holding arm 30', for example sitting on the intermediate piece 64, the fastening area 106 is arranged approximately centrally between the fastening areas 104 and 108 and is connected, for example, to a holding projection 116 sitting on the intermediate body 66, in particular centrally thereof, and the fastening area 108 is connected to a projection 118 of the holding arm 30 arranged on the end piece 68, for example in a central area of ​​the end piece 68 between the intermediate body 66 and the end 34.

[0454] The connection between the respective connecting elements 114, 116 and 118 of the holding arm 30' is rigid and free of play, preferably by welding or gluing, which does not allow any elasticity of movement between the deformation transmission element 102 and the connecting elements 114, 116 and 118.

[0455] Preferably, the connecting elements 114, 116, and 118 are also rigidly connected to the support arm 30', in particular, integrally formed thereon. The force detection module 100, the deformation transmission element 102, the connecting elements 114, 116, 118, the deformation sensors 172, 174, 176, 178, the reference deformation sensors 182, 184, 186, 188, the Wheatstone bridges 212, 214, 216, 218, the evaluation unit 230, and the circuit board 240 with the encapsulation material 242, as well as the temperature sensors 252, 254, 256, 258, are designed in the same manner in the fifth embodiment as described in the first to fourth embodiments and also operate in the same manner.

[0456] In all the embodiments described above, a calibration is carried out to determine a relationship between a measured value vector M for the sensor values ​​representing the deformation values ​​D152, D154, D156, D158 corresponding to the measured voltages UD152, UD154, UD156 and UD158 and a value WF generated by the evaluation unit 230 or 230' X , WF y and WFz for the force components representing vector K are determined by a transformation matrix T, as shown in Fig. 41.

[0457] Since the force vector K contains the three force components with the values ​​WF X , WF y and WFz, for example, only three of the deformation values ​​from the sensor values ​​UD152, UD154, DU156 and UD158, for example the deformation values ​​D152, D154 and D156, are used to form the measured value vector M.

[0458] Such a measured value vector M must then be multiplied by the transformation matrix T in order to obtain the individual values ​​WF X , WFz and WF y of the force components of the force vector K, as shown in Fig. 41.

[0459] The transformation matrix T in this case has nine transformation coefficients tlx, t2x, t3x, tl y , t2 y , t3 y , tlz, t2z, t3z.

[0460] To determine these transformation coefficients tix to t3z, as shown in Fig. 42, the holding arm 40, for example with the pivot bearing body 52, is fixed in place on a test bench and is acted upon by a force-loaded arm KA with different forces in different spatial directions.

[0461] For example, the arm KA is moved with a force F x in X-direction, and / or with a force F z in Z-direction and / or with a force F yin the Y direction or with one or more combinations of these forces.

[0462] As already mentioned, in the simplest case, a transformation matrix T valid for all spatial directions x, y, z is stored in the memory 236, with which the deformation values ​​D152, D154, D156 can be converted into values ​​WF X and WF Z and WF y for the force components acting on the coupling element 40.

[0463] In such a calibration (Fig. 42), three calibration processes are carried out one after the other, and for example, in the first calibration process only with the force component F x , and in the third calibration process only with the force component F y or only with the force component F z on the coupling element 40 and the deformation values ​​D152, D154 and D156 are then recorded during each calibration process.

[0464] Since in each of the three calibration processes mentioned the other force components F y and F z or F x and F z or F x and F y are zero, after all three calibration processes a system of equations with nine equations results for the determination of the total of nine unknown transformation coefficients tix to t3z.

[0465] However, it is also possible to work with the deformation values ​​D152, D154, D156, D158 from all four sensor values ​​UD152, DU 154, UD156 and UD158, as shown in Fig. 43, in this case a total of four calibration processes are required to determine the total of twelve transformation coefficients tix to t4 Z to obtain a total of twelve equations for the twelve unknown transformation coefficients tix to t4z. During calibration, the force F zin the direction of gravity when the support arm 30 is aligned as in a motor vehicle 10 standing on a substantially horizontal plane.

[0466] The force F x also acts when the support arm 30 is aligned as in the case of a motor vehicle 10 standing on a substantially horizontal surface in a substantially horizontal direction, in particular in a vertical vehicle longitudinal center plane 18 and thus also in the vertical longitudinal center plane 18 of the support arm 30.

[0467] Furthermore, the force F y transversely, in particular perpendicular to the vertical longitudinal center plane 18 and perpendicular to the force F x and to the force F z .

[0468] The assumed physical relationship between the exerted forces F x , F y , F z and the resulting deformations represents the simplest possible assumption.

[0469] An improvement in the quality of the results for the values ​​WF X , WF Z and WF y can be achieved if the calibration for each of the octants I to VIII arranged in the space around the coupling element 40 according to Fig. 21 and Fig. 44 lying value pairs WF X , WF Z and WF y so that it is also possible to determine non-linear spatial correlations between the forces F acting on the coupling element 40 z , F z , F y and the digital deformation values ​​of the stresses UD152, UD154, UD156 and UD158 into the calibration and thus transformation of these deformation values ​​D152, D154, D156 and D158 into the values ​​WF X , WF Z and WF y for the forces acting on the coupling element 40.

[0470] This increases the accuracy of the determined values ​​WF X , WF Z and WF ysignificantly improved. For calibration with respect to octants I to VIII, shown in Fig. 44, the forces F x , F y and F z each selected so that they lie within the respective octant and, in particular, all act towards the same point on the coupling element 40.

[0471] For example, to determine the transformation matrix TI for the octant I, only forces with force components Fxl, Fzl and F lying within it are considered. y I used.

[0472] This allows values ​​WF to be determined for the space within the respective octants I to VIII X , WF Z and WF y the force components can be determined even more precisely.

[0473] Since when determining an unknown force on the coupling element 40 its orientation and thus also its assignment to one of the octants is unknown, the components WF are determined, for example X , WF y and WF Z of the same either with the transformation matrix T determined for all spatial directions or with one of the transformation matrices TI to TVIII and subsequently the evaluation unit 230 or 230' uses the values ​​WF X , WF y and WF Z checked to which of the octants, for example octant III, the force is to be assigned and then the values ​​WF are determined again X , WF y , WF Z using the transformation matrix determined for this octant, for example the transformation matrix Till.

[0474] In order to carry out a load analysis based on the deformation values ​​D152, D154, D156, D158 using the load analysis level 233 and / or load-related forces F x , F y , F z To determine the coupling element 40, a state evaluation unit 270 is provided, as shown in Fig. 45, which interacts with the evaluation unit 230 and in particular has a sequence control 280. The sequence control 280 first checks in a state detection stage 282 whether a voltage supply to the evaluation unit 230 is sufficient.

[0475] The condition detection stage 282 checks, for example, with a voltage sensor 302, the battery voltage of the vehicle, in particular the voltage applied to the deformation sensors 182, 184, 186, 188 and, if applicable, the temperature sensors 252, 254, 256, 258 as well as the evaluation unit 230.

[0476] In particular, the state detection stage 282 also checks whether the motor vehicle 10 is in a state permissible for detecting the forces on the support arm, that is to say whether the vehicle is essentially on a horizontal plane, wherein an essentially horizontal plane is given when the deviation from an exactly horizontal plane is a maximum of ± 2°, even better ± 1° in each plane direction.

[0477] For this purpose, the state detection stage 282 checks the orientation of the vehicle with the device according to the invention relative to an orientation of the vehicle on a predetermined horizontal plane using one or more inclination sensors 304 (Fig. 3 and Fig. 45), wherein the inclination sensor 304 can be provided, for example, in the sequence control 280 or can be provided in the motor vehicle 10 or on the carrier unit 20 and is queried by the state detection stage 282.

[0478] In the event of a significant deviation of the vehicle's alignment from an alignment on the specified horizontal plane, for example, the condition detection stage 270 is deactivated in the event of large deviations.

[0479] Furthermore, in the state detection stage 282, the position of the holding arm 30 is checked to determine whether it is in the working position or outside of it. To this end, the state detection stage 282 uses a sensor set 306 (Fig. 3 and Fig. 45) to check the working position and / or other positions of the holding arm 30. At least one check of the working position is performed, and if this is not present, this check is evaluated as negative.

[0480] If, on the one hand, a sufficient voltage supply is determined in the state detection stage 282, and on the other hand, an unnecessary or executable inclination correction of the motor vehicle 10 and, moreover, the presence of the working position of the holding arm 30 is determined, the evaluation unit 230 is activated in an activation stage 284 which is then used, so that it determines the deformation values ​​D152, D154, D156, D158 for the current state of the motor vehicle 10 with the holding arm 30.

[0481] During the activation of the evaluation unit 230, an inclination correction stage 283 is also activated.

[0482] By activating the inclination correction stage 283 of the evaluation unit 230, in the case of compensable deviations, the deformation values ​​D152, D154, D156, D158 are corrected with stored inclination correction data, which were determined, for example, by a calibration process, for use in the load analysis stage 233 and / or in the force analysis stage 234.

[0483] After the state detection stage 282 has identified a permissible state for detecting the forces acting on the support arm 30, in particular on its coupling element 40, and the activation stage 284 has activated the evaluation circuit 230, optionally with the inclination correction stage 283, a zero-load detection control stage 286 is preferably used as the next step. In the zero-load detection control stage 286, it is first checked whether the load acting on the support arm 30 at zero load—i.e., no load—can be detected at all, in particular the load acting when no external force is acting on the coupling element 40 of the support arm 30.

[0484] The zero load detection control stage 286 activates, for example, a zero load value memory 312i of a zero load correction stage 285, which takes over the deformation values ​​D152, D154, D156, D158 converted by the A / D converter 232 at the time of activation and possibly corrected by the inclination correction stage 283 and stores them as deformation values ​​Dol52, Dol54, Dol56, Dol58 which are determined without external force, i.e. at zero load.

[0485] These values ​​stored in the zero-load value memory 312i of the zero-load correction stage 285 are then compared, if necessary, with stored reference values ​​DR152, DR154, DR156, DR158 present in a zero-load reference memory 3122 for a state of the holding arm 30, in particular of the coupling element 40, at zero load in order to carry out a plausibility check as to whether a load on the holding arm 30, in particular of the coupling element 40, by an external force can be excluded.

[0486] These values ​​stored in the no-load reference memory 3122 are recorded, for example, by previous or factory determinations of the corresponding deformation values ​​at no load.

[0487] In addition, the zero load detection control stage 286 checks how long the time period has passed between the last movement of the holding arm 30 into the working position and the current time.

[0488] If, for example, it is determined that the movement of the holding arm 30 and the coupling element 40 into the working position occurred only a few seconds ago, it can be assumed that no external force is yet acting on the coupling element 40 and thus the zero load can be determined.

[0489] A further possibility is that the zero-load detection control stage 286 activates a camera system 314 on the motor vehicle 10 (Fig. 1, Fig. 45), which is, for example, integrated into or comprised by the rear view camera system of the motor vehicle 10 and is capable of optically detecting whether or not an object, in particular a tow ball coupling or a load carrier, is effectively engaging the coupling element 40 and thus the holding arm 30.

[0490] Another possibility is that the zero-load detection control stage 286 activates a sensor system 316 (Fig. 2, Fig. 45), for example comprising a set of ultrasonic sensors, which are integrated in particular in the rear bumper unit 50 and are also capable of detecting whether or not an object acts on the support arm 30 and the coupling element 40.

[0491] Another possibility for checking whether no object acts on the coupling element 40 and thus the holding arm 30 is for the zero load detection control stage 286 to check whether a socket 31 assigned to the device for the electrical supply of a trailer or a load carrier unit is active, i.e. whether a supply plug is plugged into this socket 31 (Fig. 2, Fig. 45).

[0492] If a power plug inserted into the socket 31 is detected by a sensor 318 assigned to the socket 31, it can be assumed that an object is acting on the coupling element 40 and / or the holding arm 30, so that no-load detection is possible.

[0493] Based on one or more of the information explained above, the zero-load memory 312 of the zero-load correction stage 285 is then activated to store the deformation values ​​supplied by the evaluation unit 230 as deformation values ​​Dol52, Dol54, Dol56, Dol58 at zero load, which correspond to a state of the holding arm 30 and the coupling element 40 without external force.

[0494] However, if the zero load detection control stage 286 does not detect a condition in which the detection of a zero load condition is possible, for example, the deformation values ​​stored in the zero load memory 3122 during the last detection of the zero load are not replaced by the values ​​just stored in the zero load value memory 312i, but are used further and the values ​​stored in the zero load memory 312i are deleted.

[0495] A zero load correction is then carried out using the deformation values ​​Dol52, Dol54, Dol56 and Dol58 then available in the zero load value memory 3122 of the zero load correction stage 283.

[0496] After passing through the zero load detection control stage 286, a load detection control stage 288 is activated.

[0497] The load detection control stage 288 serves to operate the zero-load correction stage 285 in such a way that it only detects deformation values ​​of the force components acting on the coupling element 40 and the holding arm 30 due to the load.

[0498] For this purpose, the load sensing control stage 288 preferably checks whether an on-board function of the motor vehicle 10 is activated, for example, whether the operation of all electrical components is activated. This is done, for example, by querying a suitable on-board voltage via sensor 302.

[0499] Furthermore, the load sensing control stage 288 checks, by accessing the sensor 318, whether a socket 31 associated with the device is activated, the activation of which indicates the presence of an external force acting on the coupling element 40, be it from a trailer or a load-carrying unit (Fig. 45).

[0500] Furthermore, the load detection control stage 288 checks by means of a sensor 322 or by querying a vehicle control whether the vehicle is stationary or is moving at a speed of less than 5 km / h or is moving faster, so that at less than 5 km / h a motor vehicle 10 can be assumed to be stationary in principle for the load detection (Fig. 45).

[0501] In addition, the load detection control stage 288 also checks, for example, with the camera system 314, whether an external object, for example a trailer or a load carrier unit, is attached to the coupling element 40 and / or the load detection control stage 288 checks by means of the camera system 314 and / or the sensor system 316 whether an external object, for example a trailer or a load carrier unit, is attached to the holding arm 30 and the coupling element 40.

[0502] If necessary, the load detection control stage 288 additionally checks by means of the sensor 306 whether the holding arm 30 with the coupling element 40 is in the working position in which a trailer can be attached or a load carrier unit can be mounted.

[0503] If the load detection control stage 288 detects that an external object is acting on the coupling element 40 and the holding arm 30, the load detection control stage 288 causes, on the one hand, the deformation values ​​D152, D154, D156, D158 to be taken over from the zero load correction stage 285 and, on the other hand, the values ​​Dol52, Dol54, Dol56, Dol58 to be taken over from the zero load memory 3122 and these values ​​to be subtracted from the values ​​D152, D154, D156, D158 (Fig. 45), so that the resulting deformation values ​​D152I, D154I, D156I, D158I are available, which are the load-related deformation values ​​for the external force components F acting on the holding element 30 and the coupling element 40 x , Fz, F yrepresent. Based on the then available load-related deformation values ​​D152I, D154I, D156I, D158I, the evaluation unit 230 then determines, by means of the load analysis stage 233, using program code and a processor by applying one or more analysis methods, various load conditions of the support arm 30, without determining the force components F x . F y , and Fz is required by the described transformations.

[0504] A possible load condition concerns, for example, the detection of whether a bicycle carrier 350 is engaging the coupling element 40 of the holding arm 30, as shown in Fig. 47, or whether a trailer 360 is engaging the coupling element 40, as shown in Fig. 46.

[0505] The analysis methods applied for this purpose assume, for example, that the bicycle carrier 350 acts on the support arm 30 and in particular the deformation regions 82 and 84 in such a way that both the deformation region 82 and the deformation region 84 experience significant bending forces BX and BZ, which arise due to the bicycle carrier 350, while the proportion of pure tensile forces ZX is small, so that both deformation regions react with similar deformations.

[0506] However, if a trailer 360 is attached to the coupling element 40, the trailer 360 rests on the coupling element 40 with a support load on the one hand, which leads to a force FZ, and on the other hand, the trailer 360 acts on the coupling element 40 with a force FX, depending on the mass of the latter when the vehicle accelerates, but not when the vehicle is stationary or traveling at a negligible speed.

[0507] If the analysis procedure carried out by the load analysis stage 233 is carried out when the vehicle is stationary or at a negligible speed (less than 5 km / h), the tensile forces ZX on the load areas 82 and 84 are small, if not negligible, unless the vehicle is on an inclined surface, in which case

[0508] - at least partially - can be compensated by the inclination correction stage 283.

[0509] In Fig. 48 and 49, measured deformation values ​​D152 / I, D154 / I for the highly support load-sensitive deformation range 82 and D156 / I, D158 / I for the weak support load-sensitive deformation range 84 for a trailer 350 and a bicycle carrier 360 are shown as examples, wherein in each case a low load on the holding arm 30 is shown, marked with MIN in the figures, and a maximum load is shown in the figures, marked with MAX.

[0510] For example, in the trailer 350 shown in Fig. 46, the strain values ​​D156I and D158I of the weakly support load-sensitive deformation region 84 are close to zero, while at the minimum load, the deformation values ​​D152I and D154I of the highly support load-sensitive deformation region 82 are approximately equal and have larger values ​​than the deformation values ​​D156I and D158I. (Fig. 48)

[0511] At maximum load by means of the trailer 350, the deformation values ​​D156I and D158I of the weakly support load-sensitive deformation range 84 are still close to zero, while the deformation values ​​D152I and D154I of the strongly support load-sensitive deformation range 82 are greater than at minimum support load.

[0512] This is because the bending moments BZ caused by the support load FZ cause very small, possibly negligible, deformations in the deformation region 84, while in the deformation region 82 further away from the coupling element 40, the deformations D152I and D154I caused by the bending moments BZ are always greater and are therefore also greater at maximum support load FZ than at minimum support load FZ. In contrast, the deformation values ​​for a bicycle carrier 360 shown in Fig. 47 exhibit a different behavior. (Fig. 49)

[0513] For example, the deformation values ​​D156I and D158I are significantly different from zero and, at minimal load, are at values ​​that are lower than the deformation values ​​D152I and D154I, but qualitatively of a similar magnitude.

[0514] This is because significant bending forces BX and BZ occur due to the bicycle carrier 360, which have a significant effect on both the deformation region 82 and the deformation region 84, whereby - as Fig. 49 shows - the effects on the deformation region 84 are smaller than on the deformation region 82.

[0515] However, if a maximum load on the coupling element 40 is reached by the bicycle carrier 360, Fig. 49 shows that the deformation values ​​D156I and D158I are even greater and may differ more than with a low load and the sizes of the deformation values ​​D156I and D158I are close to the maximum permissible deformation values.

[0516] The differences between the deformation values ​​D156I and D158I as well as D152I and D154I measured on different sides of the longitudinal center plane at maximum load by the bicycle carrier 360 result in part, for example, from a force FY caused by an uneven loading of the bicycle carrier on different sides of the coupling element 40 or from an asymmetry of the holding arm 30, which is caused, for example, by the fact that the holding arm 30 and the pivot axis 54 running obliquely to the longitudinal center plane 18 are pivotally mounted.

[0517] The load analysis stage 233 can now distinguish between a trailer 350 engaging the coupling element 40 or a bicycle carrier 360 engaging the coupling element 40 using different analysis methods.

[0518] First, each of the analysis methods described below checks whether the deformation values ​​D152I, D154I, D156I, and D158I lie within a permissible range between the values ​​DO and Dmax. If this is the case, the further analysis is started.

[0519] The first and simplest analysis method provides for checking, according to a first analysis criterion, whether deformation values, namely the deformation values ​​D156I and D158I of the weakly support load-sensitive deformation range 84, are close to DO, in contrast to the deformation values ​​D152I and D154I of the strongly support load-sensitive deformation range 82.

[0520] In particular, according to the first analysis criterion, the deformation values ​​D156I and D158I are compared with a predetermined first reference value range RBO comprising the value DO, which, for example, comprises the value DO plus / minus 5% of Dmax.

[0521] If the deformation values ​​D156I and D158I are in this first reference value range RBO, a first criterion for the presence of a trailer 350 on the coupling element 40 is given.

[0522] Thus, a result is already available with the first analysis criterion for differentiating between a trailer 350 engaging the coupling element 40 or a bicycle carrier 360 engaging the coupling element 40.

[0523] Furthermore, when applying a second analysis method, a second analysis criterion is that all deformation values ​​D156I, D158I, D152I, and D154I for the bicycle carrier 360 are significantly different from D0. The second analysis criterion provides, for example, a threshold value S for the deformation values ​​D156I, D158I, D152I, and D154I as a second reference value, which is, for example, 5% or, for example, 10% of Dmax. If all deformation values ​​D156I, D158I, D152I, and D154I are above this threshold value S, the bicycle carrier 360 is assumed to be engaging the holding element 40. (Fig. 49)

[0524] With this second analysis criterion, in particular in conjunction with the first analysis criterion, the engagement of a trailer 350 can be distinguished from the engagement of a bicycle carrier 360 on the coupling element 40.

[0525] A third analysis criterion used in a third analysis method provides for determining the difference DI between the deformation value D152I of the highly support load-sensitive deformation region 82 and the corresponding deformation value D156I of the weakly support load-sensitive deformation region with respect to its position relative to the longitudinal center plane 18, or between the deformation value D154I of the highly support load-sensitive deformation region 82 and the corresponding deformation value D158I of the weakly support load-sensitive deformation region 84 with respect to its position relative to the longitudinal center plane 18, and relating this difference to the respective absolute values ​​of the deformation values ​​D152I or D154I or D156I or D158I. (Fig. 48, Fig. 49)

[0526] As Fig. 48 clearly shows, the above-mentioned difference in the case of a trailer 350 is approximately in the order of magnitude of the absolute values ​​of the deformation values ​​D152I or D154I of the deformation region 82 which is highly sensitive to the support load, while - as can be seen in Fig. 49 - the above-mentioned difference in the case of a bicycle carrier 360 is only a fraction of the deformation values ​​D152I or D154I.

[0527] The third analysis criterion, for example, provides as predefined reference values ​​a trailer reference value band RAWB that lies between the largest of the deformation values ​​D152I and D154I of the highly support load-sensitive deformation range 82 and 50% of the largest of the deformation values ​​D152I and D154I of the highly support load-sensitive deformation range 82 and a bicycle carrier reference value band R.FWB that lies between 50% of the largest of the deformation values ​​D152I and D154I of the highly support load-sensitive deformation range 82 and DO, and depending on whether the difference DI lies in the trailer reference value band RAWB or the bicycle carrier reference value band R.FWB, a distinction can be made between a trailer 350 and a bicycle carrier 360.

[0528] This third analysis criterion also makes it possible to distinguish between a trailer 350 engaging the coupling element 40 or a bicycle carrier 360 engaging the coupling element 40.

[0529] Thus, the load analysis stage 233 is able to transmit to a communication stage 290 of the condition evaluation unit 270 either a signal for a trailer 350 engaging the coupling element 40, for example signal A, or a signal for a bicycle carrier 360 engaging the coupling element 40, for example signal F.

[0530] The communication stage 290 is further capable of communicating with the vehicle, in particular the vehicle electronics, and transmitting these signals, for example, to a speed monitoring system 322 of the vehicle or a stabilization system 326 or a chassis control system 328 of the motor vehicle in order to be able to adapt the speed, the chassis stabilization and the chassis setting depending on operation with a trailer 350 or a bicycle carrier 360.

[0531] Furthermore, the communication stage 290 can also interact with a presentation stage 292, which, for example, presents the fact that operation is being carried out with a trailer 350 or a bicycle rack 360 to the driver on a display 294. However, the operation of the load analysis stage 233 can also be simplified even further.

[0532] A further simplified mode of operation provides for only one of the deformation values ​​D152I and D154I and D156I and D158I to be used for the analysis criteria, for example the deformation values ​​D152I and the deformation values ​​D156I or D154I and D158I, i.e. the deformation values ​​recorded by the sensors 152 and 156 or 154 and 158, which lie on the same side of the longitudinal center plane 18.

[0533] These deformation values ​​D152I and D156I or D154I and D158I also allow the different behavior of the deformation areas 82 and 84 in a trailer 350 or bicycle carrier 360 to be recognized when applying the three analysis criteria described above and can thus be used to recognize a trailer or a bicycle carrier.

[0534] The stress analysis level 233 can also work with a simplified mode of operation.

[0535] A simplified operating method provides for the formation of a deformation mean value D82I and D84I from the deformation values ​​D152I and D154I for the highly support load-sensitive deformation range 82 and D156I and D158I for the weak support load-sensitive deformation range 84 and for evaluating these using the analysis methods as shown in Fig. 50 and 51.

[0536] Both the first analysis criterion and the second and third analysis criteria can be applied analogously to these deformation mean values ​​D82I and D84I, since the different behavior of the deformation areas 82 and 84 is also reflected in the deformation mean values ​​D82, formed from D152I and D154I, and D84, formed from D156I and D158I, namely in that the deformation mean value D84 for the trailer 350 is close to DO and essentially only the deformation mean value D82 is significantly different from DO, while for a bicycle carrier 360 the deformation mean values ​​D82 and D84 are significantly different from DO.

[0537] Unless the determination of the three force components F x , F y and F zis provided, the force detection module 100 according to the invention can also have only two deformation concentration regions, namely one to which the deformations in the highly support load-sensitive deformation region 82 and one to which the deformations in the weak support load-sensitive deformation region 84 are transferred and then detected by the deformation sensors assigned to them.

[0538] In such a simplified embodiment, the respective deformation concentration regions are preferably located close to or in the longitudinal center plane 18 of the holding arm 30.

[0539] The load detection control stage 288 can also simultaneously activate the force analysis stage 234 in the evaluation circuit 230 or 230', which then determines the values ​​WFxl, WFzl and WFyl and can thus determine the load-related forces on the holding element 30 and the coupling element 40, which can represent the external force components F acting on the holding element 30 and the coupling element 40 x , F z and F y represent.

[0540] These force components F x , F z and F y can be transmitted to the communication stage 290, which also transmits these force components to the cruise control 322 as well as to the stabilization system 326 and the chassis control 328.

[0541] Likewise, the communication stage 290 transmits these values ​​to the presentation stage 292, which then displays these forces, for example, on the display 294. Another possible load condition, namely a rough estimate of the magnitude of the total load without determining the forces F x , F y or Fz is carried out using a fourth analysis method.

[0542] In the fourth analysis method, the size of one or both of the highly support load-sensitive deformation values ​​D152I and D154I or the deformation mean value D82 of the support load-sensitive deformation range 82 is determined if a trailer 350 is detected by one or more of the first to third analysis criteria, or the size of one or both of the less support load-sensitive deformation values ​​D154I, D156I or the deformation mean value D84 of the less support load-sensitive deformation range 84 is determined in order to recognize how large the forces acting on the coupling element 40 are in the case of a bicycle carrier 360.

[0543] The determination of the load on the coupling element 40 using the load reference values ​​B1 to B6 is carried out, as can be seen in Fig. 48 to 51, by determining between which of the load reference values ​​B1, B2, B3, B4, B5, B6 the respective deformation values ​​D152I, D154I, D156I and D158I or the deformation mean values ​​D82 or D84 lie, so that, for example, five load segments BS1 to BS5 result, into which the deformation values ​​or deformation mean values ​​can be classified and which can be forwarded as load segments BS1 to BS5 by the load analysis stage 233 via the communication stage 290 in the manner already described (Fig. 45).

[0544] This can be done, for example, using one or more predetermined load reference values ​​B1 ... B6, and at least qualitatively determining the magnitude of the total forces acting on the coupling element 40, without the magnitude of the forces having to be determined absolutely. Furthermore, in a fifth analysis method, using a fifth analysis criterion, by comparing exclusively with a maximum load reference value B6 in Figs. 48 to 51, it can be determined to what extent an overload is occurring, i.e., whether the load reference value B6 has been exceeded, or whether an overload is imminent, i.e., whether the load reference value B6 is about to be reached, and this information is also forwarded as a warning signal WB by the communication stage 290 (Fig. 45).

[0545] Other possible load conditions concern the behavior of a trailer 360, in particular its dynamic behavior while driving.

[0546] The prerequisite for determining these load conditions is the determination that a trailer 350 acts on the coupling element 40, according to one or more of the first to third analysis methods.

[0547] In a sixth analysis method, a time-resolved recording of the individual deformation values ​​D152I, D154I, D156I and D158I is carried out using a sixth analysis criterion while the vehicle is moving in order to detect sudden changes in the same.

[0548] This is the case, for example, if all deformation values ​​show a short-term change in the deformation values ​​D152I, D154I, D156I and D158I for a trailer 350 that is attached and recognized as such with the first three analysis criteria, as shown in Fig. 52, and all deformation values ​​D show an increase or a decrease in value.

[0549] In this case, an additional evaluation of the steepness F5 of the flanks F of the short-term changes and / or a time duration Z of an increase in the respective deformation value D from a previous initial value up to a maximum value is carried out, from which conclusions can be drawn about the functioning of a brake of the trailer 350 or other problem-related behaviors of the trailer 350, which lead to a sudden change in the deformation values ​​D up to the maximum value, in particular in both deformation ranges 82 and 84, and for example in time periods Z which are shorter than a reference period ZR of, for example, less than 0.5 seconds.

[0550] For example, if an overrun brake of the trailer 350 is functioning correctly, a low edge steepness FS or a long time period Z is detected, or if the overrun brake is not functioning correctly, an exceeding of a predetermined reference value RFS for the edge steepness FS and / or a time period Z that is shorter than a stored reference time period RZ is detected, and then a warning signal WA is generated and forwarded by the communication unit 290 (Fig. 45).

[0551] Further analysis methods for evaluating the dynamic behavior of a trailer 350 are the seventh and eighth analysis methods described below.

[0552] In the seventh and eighth analysis methods, shown in Fig. 53, after detecting a trailer 350 engaging the coupling element 40 while the vehicle is traveling, time-resolved antiphase oscillations corresponding to variations in the deformation values ​​D152I, D154I of the deformation section 82 recorded on opposite sides of the longitudinal center plane 18 and the deformation values ​​D156I and D158I of the deformation section 84 recorded on opposite sides of the longitudinal center plane 18 are recorded, each relative to a mean value M152, M154, M156 and M158, in order to detect transverse forces acting transversely to the direction of travel on the coupling element 40, which result, for example, from a rolling movement of the trailer 350, wherein the amplitude AS of the oscillations represents a measure of the strong rolling movement and / or a period PS of the rolling movements generated vibrations are preferably in the range greater than 1 second.A seventh analysis criterion compares the amplitude AS of the oscillations with a predetermined reference value RAS and an eighth analysis criterion compares the period duration PS of the oscillations with a predetermined reference value RPS in order to detect whether the trailer 350 is swaying in a way that endangers the towing vehicle and to then output a warning signal WS, which is forwarded by the communication unit 290 (Fig. 45).

Claims

PATENT CLAIMS Method for operating a device for coupling a trailer and / or a load carrier unit (360), which can be mounted at the rear of a motor vehicle body, comprising a holding arm (30) which is fixedly connected to the motor vehicle body (12) at a first end (32) during operation and which carries a coupling element (40) for the trailer (350) and / or the load carrier unit (360) at a second end, wherein forces acting on the coupling element (40) during operation and transmitted by the holding arm (30) to the motor vehicle body (12) are detected by an evaluation unit (230) by means of deformation sensors (172, 174, 176, 178), wherein the holding arm (30) has at least two deformation areas (82, 84), the deformation behavior of which is each detected by at least one deformation sensor when a force acts on the holding arm (30). (172, 174, 176, 178) is recorded, which corresponds to the respective deformation area (82,84) of the retaining arm (30) is rigidly coupled and thereby detects its deformation behavior, characterized in that the evaluation unit (230) has a load analysis stage (233) which, starting from the deformation values ​​(D152, D154, D156, D158) of the at least two deformation areas (82, 84) determined by the deformation sensors (172, 174, 176, 178), determines at least one load type of the retaining arm (30) using analysis methods. Method according to claim 1, characterized in that the load analysis stage (233) converts the deformation values ​​(D152, D154, D156, D158) into forces in the vertical direction (F, z ) and / or in the longitudinal direction of the vehicle (24) and / or transversely to the longitudinal median plane of the vehicle (F y ) uses. A method according to any one of the preceding claims, characterized in that the at least one analysis method is a value comparison method. A method according to any one of the preceding claims, characterized in that, in the value comparison method, the deformation values ​​(D) are compared with each other and / or with reference values ​​(RBO, S, RAWB, RFWB, B1...B6, RFS, ZR, RAS, RPS). A method according to claim 4, characterized in that the reference values ​​are predetermined, in particular stored, reference values ​​(RBO, S, RAWB, RFWB, B1...B6, RFS, ZR, RAS, RPS). A method according to claim 4 or 5, characterized in that the reference values ​​(RBO, S, RAWB, RFWB, B1...B6, RFS, ZR, RAS, RPS) are determined by tests. A method according to claim 6, characterized in that the reference values ​​are determined by load tests of a representative support arm (30).A method according to any one of the preceding claims, characterized in that absolute values ​​of the load-induced deformation values ​​(D) are evaluated in at least one analysis method. A method according to claim 8, characterized in that one analysis criterion is based on a comparison of the absolute values ​​of the load-induced deformation values ​​(D) with threshold values ​​(S) as reference values. A method according to claim 8 or 9, characterized in that at least one analysis criterion is based on a comparison of each of the... Absolute values ​​of the load-induced deformation values ​​(D) are compared with a stored reference value range (RBO). A method according to one of the preceding claims, characterized in that, in at least one analysis method, at least one deformation value (D) of a deformation area (82) is compared with at least one deformation value (D) of at least one other deformation area (84). A method according to one of the preceding claims, characterized in that the analysis method is based on a comparison of the behavior of the deformation values ​​(D152, D154) of a highly load-sensitive deformation area relative to a weakly load-sensitive deformation area. A method according to claim 11 or 12, characterized in that, in the analysis method, the difference between the two deformation values ​​(D) is determined.A method according to claim 13, characterized in that the analysis method determines the ratio of the difference between the two deformation values ​​(D) relative to the largest of the two deformation values ​​(D). A method according to any one of claims 11 to 14, characterized in that an analysis criterion is based on a comparison of the behavior of at least one deformation value (D152, D154) of a highly load-sensitive deformation region (82) relative to at least one deformation value (D154, D156) of a weakly load-sensitive deformation region (84). A method according to claim 15, characterized in that the analysis criterion is based on the ratio of the difference between the deformation values ​​(D) and the largest of the two deformation values ​​(D) in comparison with stored reference value ranges (RAWB, RFWB). A method according to any of the preceding claims, characterized in that the magnitude of the load-induced deformation value (D152, D154, D156, D158) determined for at least one deformation range (82, 84) is determined by an analysis method by comparing this load-induced deformation value (D152, D154, D156, D158) with at least one load reference value (B1...B6) specified for this deformation value. A method according to claim 17, characterized in that the analysis method assigns the at least one load-induced deformation value (D152, D154, D156, D158) to several specified load reference values ​​(B1...B6) is achieved by assigning the at least one actual deformation value (D152, D154, D156, D158) to the ranges (BS1, BS2, BS3, BS4, BS5) between any two successive load reference values ​​(B1...B6). A method according to claim 17 or 18, characterized in that an analysis criterion is based on the assignment of the at least one of the deformation values ​​relative to the series of at least three load reference values ​​(B1 to B6) provided for this deformation value. A method according to one of the preceding claims, characterized in that, in an analysis method, a comparison of at least one of the deformation values ​​(D152, D154, D156, D158) is performed. with an associated maximum load reference value (B6). Method according to claim 20, characterized in that an analysis criterion is based on the assignment of the load-induced deformation value to at least one of the load-induced deformation values ​​(D152, D154, D156, D158) relative to a maximum load reference value (B6) assigned to the deformation value. Method according to any of the preceding claims, characterized in that an analysis method detects at least one of the load-induced deformation values ​​(D152, D154, D156, D158) with time resolution. Method according to claim 22, characterized in that an analysis criterion is based on a short-term change in at least one of the deformation values ​​(D152, D154, D156, D158). Method according to claim 23, characterized in that the analysis method detects a slope behavior of at least one of the actual deformation values ​​(D152, D154, D156, D158).The method of claim 24, characterized in that an analysis criterion compares a slope (FS) of the gradient behavior with a stored reference value (RFS). The method of claims 22 to 25, characterized in that the analysis method determines the time period (Z) of an increase of at least one of the load-induced deformation values ​​(D) up to a maximum value. A method according to any one of claims 22 to 26, characterized in that an analysis criterion is based on comparing the time duration (Z) with a reference time (RZ). A method according to any one of claims 22 to 27, characterized in that an analysis criterion is based on a temporal profile of at least one of the deformation values. A method according to any one of claims 22 to 28, characterized in that the analysis method captures a temporal profile of an oscillation of at least one of the deformation values ​​(D152, D154, D156, D158) around a mean value of this oscillating deformation value (D152, D154, D156, D158). Method according to claim 29, characterized in that an analysis criterion is based on a comparison of an amplitude (AS) of oscillations of one of the load-induced deformation values ​​(D152, D154, D156, D158) around the mean value with a reference value (RAS).A method according to claims 28 to 30, characterized in that an analysis criterion is based on a comparison of a period (PS) of one of the load-induced deformation values ​​with a reference period (RPS). A method according to the preamble of claim 1 or according to one of the preceding claims, characterized in that each deformation value (D) used by the load analysis stage (233) is corrected by a zero-load correction stage (285). A method according to claim 32, characterized in that a deformation value (DI) at zero load is determined by the zero load correction stage (285) and subtracted from a determined deformation value (D) under load. A method according to claim 32 or 33, characterized in that the zero load correction stage (285) is activated before the holding arm (30) is loaded. A method according to any one of claims 32 to 34, characterized in that the zero load correction stage (285) is activated after the holding arm (30) has been moved into a working position.A method according to any of the preceding claims, characterized in that each deformation value (D) used by the load analysis stage (233) is corrected by an inclination correction stage (283) which corrects the actual orientation of the support arm (30) due to an inclination of the vehicle relative to a deformation value (D) when the support arm (30) is in the orientation of a vehicle standing on a horizontal reference surface. A method according to claim 36, characterized in that the inclination correction stage (283) modifies the deformation values ​​(D) of the deformation areas (152, 154, 156, 158) such that the influence of the changed orientation of the support arm (30) relative to an orientation of the support arm (30) when the vehicle is standing on a horizontal reference surface is taken into account.Method according to claim 36 or 37, characterized in that the inclination correction stage (283) operates with stored inclination correction values. Method according to claim 38, characterized in that the inclination correction stage (283) operates with experimentally determined inclination correction values. A device for coupling a trailer and / or a load carrier unit (360) that can be mounted at the rear of a motor vehicle body, comprising a retaining arm (30) which is fixedly connected to the motor vehicle body (12) at a first end (32) during operation and which carries a coupling element (40) for the trailer (350) and / or the load carrier unit (360) at a second end, wherein forces acting on the coupling element (40) during operation and transmitted by the retaining arm (30) to the motor vehicle body (12) are detected by an evaluation unit (230) by means of deformation sensors (172, 174, 176, 178), wherein the retaining arm (30) has at least two deformation areas (82, 84) whose deformation behavior under a force acting on the retaining arm (30) is each detected by at least one deformation sensor (172, 174, 176, 178).178) is detected, which is rigidly coupled to the respective deformation area (82, 84) of the retaining arm (30) and thereby detects its deformation behavior, characterized in that the evaluation unit (230) has a load analysis stage (233) which, starting from the deformation values ​​(D152, D154, D156, D158) of the at least two deformation areas (82, 84) determined by the deformation sensors (172, 174, 176, 178) using analysis methods, determines at least one load type of the retaining arm (30). Device according to claim 40, characterized in that the load analysis stage (233) determines the deformation values ​​(D152, D154, D156, D158) without transforming them into forces in the vertical direction (F, z ) and / or in the longitudinal direction of the vehicle (24) and / or transversely to the longitudinal median plane of the vehicle (F y ) uses. Device according to any one of claims 40 to 41, characterized in that the at least one analysis method is a value comparison method. Device according to any one of claims 40 to 42, characterized in that, in the value comparison method, the deformation values ​​(D) are compared with each other and / or with reference values ​​(RBO, S, RAWB, RFWB, B1...B6, RFS, ZR, RAS, RPS). Device according to claim 43, characterized in that the reference values ​​are predetermined, in particular stored, reference values ​​(RBO, S, RAWB, RFWB, B1...B6, RFS, ZR, RAS, RPS). Device according to claim 43 or 44, characterized in that the reference values ​​(RBO, S, RAWB, RFWB, B1...B6, RFS, ZR, RAS, RPS) are determined by tests. Device according to claim 45, characterized in that the reference values ​​are determined by load tests of a representative support arm (30).Device according to any one of claims 40 to 46, characterized in that absolute values ​​of the load-induced deformation values ​​(D) are evaluated in at least one analysis method. Device according to claim 47, characterized in that one analysis criterion is based on a comparison of the absolute values ​​of the load-induced deformation values ​​(D) with threshold values ​​(S) as reference values. Device according to claim 47 or 48, characterized in that at least one analysis criterion is based on a comparison of each. The absolute values ​​of the load-induced deformation values ​​(D) are compared with a stored reference range (RBO). Device according to one of claims 40 to 49, characterized in that, in at least one analysis method, at least one deformation value (D) of a deformation area (82) is compared with at least one deformation value (D) of at least one other deformation area (84). Device according to one of claims 40 to 50, characterized in that the analysis method is based on a comparison of the behavior of the deformation values ​​(D152, D154) of a highly load-sensitive deformation area relative to a weakly load-sensitive deformation area. Device according to claim 50 or 51, characterized in that the difference between the two deformation values ​​(D) is determined in the analysis method.Device according to claim 52, characterized in that the analysis method determines the ratio of the difference between the two deformation values ​​(D) relative to the largest of the two deformation values ​​(D). Device according to any one of claims 50 to 53, characterized in that an analysis criterion is based on a comparison of the behavior of at least one deformation value (D152, D154) of a highly load-sensitive deformation region (82) relative to at least one deformation value (D154, D156) of a weakly load-sensitive deformation region (84). Device according to claim 54, characterized in that the analysis criterion is based on the ratio of the difference between the deformation values ​​(D) and the largest of the two deformation values ​​(D) in comparison with stored reference value ranges (RAWB, RFWB). Device according to any one of claims 40 to 55, characterized in that the magnitude of the load-induced deformation value (D152, D154, D156, D158) determined for at least one deformation range (82, 84) is determined by an analysis method by comparing this load-induced deformation value (D152, D154, D156, D158) with at least one load reference value (B1...B6) specified for this deformation value. Device according to claim 56, characterized in that the analysis method assigns the at least one load-induced deformation value (D152, D154, D156, D158) to several specified load reference values ​​(B1...B6) is achieved by assigning the at least one actual deformation value (D152, D154, D156, D158) to the ranges (BS1, BS2, BS3, BS4, BS5) between any two successive load reference values ​​(B1...B6). Device according to claim 56 or 57, characterized in that an analysis criterion is based on the assignment of the at least one of the deformation values ​​relative to the series of at least three load reference values ​​(B1 to B6) provided for this deformation value. Device according to one of claims 40 to 58, characterized in that in an analysis method a comparison of at least one of the deformation values ​​(D152, D154, D156, D158) with an assigned maximum load reference value (B6) is carried out. Device according to claim 59, characterized in that an analysis criterion is based on the assignment of the load-induced deformation value to at least one of the load-induced deformation values ​​(D152, D154, D156, D158) relative to a maximum load reference value (B6) assigned to the deformation value. Device according to any one of claims 40 to 60, characterized in that an analysis method detects at least one of the load-induced deformation values ​​(D152, D154, D156, D158) with time resolution. Device according to claim 61, characterized in that an analysis criterion is based on a short-term change in at least one of the deformation values ​​(D152, D154, D156, D158). Device according to claim 62, characterized in that the analysis method detects the slope behavior of at least one of the actual deformation values ​​(D152, D154, D156, D158).Device according to claim 63, characterized in that an analysis criterion compares a slope (FS) of the gradient behavior with a stored reference value (RFS). Device according to claims 61 to 64, characterized in that the analysis method determines a time period (Z) of an increase of at least one of the load-induced deformation values ​​(D) up to a maximum value. Device according to any one of claims 61 to 65, characterized in that an analysis criterion is based on comparing the time duration (Z) with a reference time (RZ). Device according to any one of claims 61 to 66, characterized in that an analysis criterion is based on a temporal profile of at least one of the deformation values. Device according to any one of claims 61 to 67, characterized in that the analysis method detects a temporal profile of an oscillation of at least one of the deformation values ​​(D152, D154, D156, D158) around a mean value of this oscillating deformation value (D152, D154, D156, D158). Device according to claim 68, characterized in that an analysis criterion is based on a comparison of an amplitude (AS) of oscillations of one of the load-induced deformation values ​​(D152, D154, D156, D158) around the mean value with a reference value (RAS).Device according to claims 67 to 69, characterized in that an analysis criterion is based on a comparison of a period (PS) of one of the load-induced deformation values ​​with a reference period (RPS). Device according to the preamble of claim 40 or according to any one of claims 40 to 68, characterized in that each deformation value (D) used by the load analysis stage (233) is corrected by a zero-load correction stage (285). Device according to claim 71, characterized in that the zero-load correction stage (285) determines a deformation value (DI) at zero load. The zero-load correction stage (285) determines the deformation value (D) and subtracts it from a determined deformation value (D) under load. Device according to claim 71 or 72, characterized in that the zero-load correction stage (285) is activated before the holding arm (30) is loaded. Device according to any one of claims 71 to 73, characterized in that the zero-load correction stage (285) is activated after the holding arm (30) has moved into a working position. Device according to any one of claims 40 to 74, characterized in that each deformation value (D) used by the load analysis stage (233) is corrected by an inclination correction stage (283), which corrects the actual orientation of the holding arm (30) due to an inclination of the vehicle relative to a deformation value (D) when the holding arm (30) is in the orientation of a vehicle standing on a horizontal reference surface.Device according to claim 75, characterized in that the tilt correction stage (283) modifies the deformation values ​​(D) of the deformation areas (152, 154, 156, 158) such that the influence of the changed orientation of the support arm (30) relative to an orientation of the support arm (30) on a vehicle standing on a horizontal reference surface is taken into account. Device according to claim 75 or 76, characterized in that the tilt correction stage (283) operates with stored tilt correction values. Device according to claim 77, characterized in that the tilt correction stage (283) operates with experimentally determined tilt correction values. Device according to the preamble of claim 40 or according to any one of claims 40 to 78, characterized in that the at least two deformation sensors (172, 174, 176, 178) of the sensor arrangement (170) are arranged on the same side of a neutral fiber of the support arm that does not vary in length during bending deformation of the support arm (30). Device according to claim 79, characterized in that a force detection module (100) is arranged on one side of the support arm (30, 30'), which comprises a sensor arrangement (170) that detects forces acting on the coupling element (40) during operation and transmitted from the support arm (30) to the vehicle body (12). Device according to claim 80, characterized in that the sensor arrangement has at least three, in particular four, deformation sensors (172, 174, 176).Device according to claim 80 or 81, characterized in that the force detection module (100) is not arranged on any side of the support arm (30, 30') facing a roadway (44) during operation. Device according to any one of claims 80 to 82, characterized in that the force detection module (100) is arranged on a side of the support arm (30, 30') facing away from a roadway (44) during operation. Device according to the preamble of claim 40 or according to any one of claims 40 to 83, characterized in that during operation... Forces acting on the coupling element (40) and transmitted by the holding arm (30) to the vehicle body (12) are detected by an evaluation unit (230) with a sensor arrangement (170) which has at least two deformation sensors (172, 174, 176), the deformation sensors (172, 174, 176, 178) being arranged on at least one deformation transmission element (102) which is connected to the holding arm (30). Device according to the preamble of claim 40 or according to one of claims 40 to 84, characterized in that forces acting on the coupling element (40) during operation and transmitted from the holding arm (30) to the vehicle body (12) are detected by an evaluation unit (230) with a sensor arrangement (170) which has at least two deformation sensors (172, 174, 176), and that all deformation sensors (172, 174, 176, 178) of the sensor arrangement (170) are arranged on a common deformation transmission element (102).Device according to one of claims 79 to 85, characterized in that each of the at least two deformation sensors (172, 174, 176) detects different deformations of the holding arm (30, 30') when one and the same force is applied to the coupling element (40). Device according to one of claims 79 to 86, characterized in that the deformation transfer element (102) is connected to the retaining arm (30) at least two fastening areas (104, 106, 108) in a relatively movement-free and thus rigid manner, and that at least one of the deformation sensors (172, 174, 176, 178) is arranged between the fastening areas (104, 106, 108) of the deformation transfer element (102). Device according to one of claims 79 to 87, characterized in that the deformation transmission element (102) is connected to the retaining arm (30) by at least three fastening areas (104, 106, 108) and that at least one of the deformation sensors (172, 174, 176, 178) is arranged between each of the fastening areas (104, 106, 108).A device according to any one of claims 79 to 88, characterized in that the deformation transfer element (102) is connected to the retaining arm (30) in the mounting areas (104, 106, 108) by means of connecting elements (114, 116, 118). A device according to claim 89, characterized in that the connecting elements (114, 116, 118) are rigidly connected on one side to the retaining arm (30) and on the other side rigidly to the mounting areas (104, 106, 108) of the deformation transfer element (102). A device according to claim 90, characterized in that the connecting elements (114, 116, 118) are integrally formed on the retaining arm (30). Device according to any one of claims 79 to 91, characterized in that the connecting elements (114, 116, 118) transmit deformations of the retaining arm (30) in deformation areas (82, 84) of the retaining arm (30) located between the connecting elements (114, 116, 118) to the fastening areas (104, 106, 108) of the deformation transmission element (102). Device according to any one of claims 89 to 92, characterized in that a deformation area (82, 84) of the retaining arm (30) is located between each pair of connecting elements (114, 116, 118).A device according to any one of claims 79 to 93, characterized in that the retaining arm (30) has at least two deformation areas (82, 84), the deformations of which are transferred via connecting elements (114, 116, 118) arranged on both sides of the respective deformation area (82, 84) to fastening areas (104, 106, 108) of the deformation transfer element (102), between which a deformation-bearing area (152, 154, 156) of the deformation transfer element (102) is located. A device according to claim 94, characterized in that the at least two deformation areas (82, 84) are arranged successively in one extension direction of the retaining arm (30). Device according to one of claims 79 to 95, characterized in that at least one deformation sensor (172, 174, 176, 178) is arranged in one of the deformation-prone areas (152, 154, 156, 158) of the deformation transfer element (102). Device according to any one of claims 94 to 96, characterized in that each deformation-prone area (152, 154, 156, 158) is connected to a deformation-stiff area (144, 146, 148) of the deformation transfer element (102) and that the fastening areas (104, 106, 108) are each located in a deformation-stiff area (144, 146, 148). Device according to claim 97, characterized in that the deformation-prone areas (152, 154, 156, 158) are each arranged between two deformation-stiff areas (144, 146, 148). Device according to claim 97 or 98, characterized in that the deformation-resistant areas (144, 146, 148) and the deformation-prone areas (152, 154, 156, 158) are arranged successively in a deformation direction. Device according to any one of claims 94 to 99, characterized in that the deformation-prone areas (152, 154, 156, 158) are designed as deformation concentration areas.A device according to any one of claims 79 to 100, characterized in that the material of the deformation transfer element (102) outside the areas subject to deformation (152, 154, 156, 158) is designed as a deformation-stiff or deformation-inert material. A device according to any one of claims 79 to 101, characterized in that the material of the deformation transfer element (102) in the areas subject to deformation (152, 154, 156, 158) is deformation-prone by a shaping, for example, a cross-sectional narrowing. Device according to any one of claims 79 to 102, characterized in that the deformation transfer element (102) has, in addition to the respective deformation-prone area (152, 154, 156, 158), a deformation-free area (192, 194, 196, 198) on which at least one reference deformation sensor (182, 184, 186, 188) is arranged. Device according to claim 103, characterized in that the respective deformation-free area (192, 194, 196, 198) is made of the same material as the deformation-prone area (152, 154, 156, 158). Device according to claim 103 or 104, characterized in that the respective deformation-free area (192, 194, 196, 198) is connected on one side to a deformation-stiff area (144, 146, 148) of the deformation transfer element (102).Device according to any one of claims 103 to 105, characterized in that the deformation-free area (192, 194, 196, 198) of the deformation transfer element (102) is tongue-shaped. Device according to any one of claims 103 to 106, characterized in that the deformation-free area (192, 194, 196, 198) of the deformation transfer element (102) is made of the same material, in particular with the same material thickness, as the deformation-prone area (152, 154, 156, 158). Device according to any one of claims 103 to 107, characterized in that the reference deformation sensors (182, 184, 186, 188) are thermally coupled to the deformation transfer element (102). Device according to claim 108, characterized in that the reference deformation sensors (182, 184, 186, 188) are thermally coupled to the deformation sensors (172, 174, 176, 178) by means of the deformation transfer element (102). Device according to claim 109, characterized in that, for optimal thermal coupling between the respective deformation sensor (172, 174, 176, 178) and the associated reference deformation sensor (182, 184, 186, 188), each deformation-prone area (152, 154, 156, 158) provided with a deformation sensor (172, 174, 176, 178) is thermally coupled with the deformation-free area (192, 194, 196, 198) associated with it and supporting the associated reference deformation sensor (182, 184, 186, 188).Device according to one of claims 103 to 110, characterized in that the deformation-free area (192, 194, 196, 198) supporting the respective reference deformation sensor (182, 184, 186, 188) has the same thermal behavior as the deformation-affected area (152, 154, 156, 158) supporting the corresponding deformation sensor (172, 174, 176, 178). Device according to one of claims 103 to 111, characterized in that the respective deformation-free area (192, 194, 196, 198) supporting the reference deformation sensor (182, 184, 186, 188) has a geometric shape comparable to the deformation-affected area (152, 154, 156, 158) supporting the deformation sensor (172, 174, 176, 178). Device according to any one of claims 103 to 112, characterized in that the deformation-free area (192, 194, 196, 198) of the deformation transfer element (102) is made of the same material as the deformation-prone area (152, 154, 156, 158) of the deformation transfer element (102). Device according to any one of claims 103 to 113, characterized in that at least one temperature sensor (252, 254, 256, 258) is assigned to the reference deformation sensors (182, 184, 186, 188) for functional monitoring. Device according to one of claims 79 to 114, characterized in that the deformation transfer element (102) is plate-like and each deformation-prone area (152, 154, 156, 158) carrying a deformation sensor (172, 174, 176, 178) is formed by a cross-sectional constriction of the deformation transfer element (102).Device according to claim 115, characterized in that the cross-sectional constriction of the deformation transfer element (102) is formed by a constriction of a surface area of ​​the deformation transfer element (102). Device according to any one of claims 79 to 116, characterized in that the deformation sensors and the reference deformation sensors are designed as strain sensors, in particular strain gauges. Device according to any one of claims 79 to 117, characterized in that the deformation sensors and the reference deformation sensors are designed as magnetostrictive or optical sensors. Device according to the preamble of claim 40 or according to any one of claims 40 to 118, characterized in that the retaining arm (30) has a first deformation area (82) and a second deformation area (84) between the first end (32) and the second end (34), which undergo deformations when a force (Fx) acts parallel to the direction of travel (24) in the longitudinal median plane (18) of the retaining arm (30), which differ from the deformations when a force (F) acts transversely to the direction of travel (24) in the longitudinal median plane (18). z ) differ. Device according to claim 119, characterized in that the first and the second deformation area (82, 84) are deformed when a force (F) acts transversely, in particular perpendicularly, to the longitudinal median plane (18) y ) each undergo deformations that differ from the deformations caused by a force F acting in the longitudinal median plane (18) parallel and / or transverse to the direction of travel (24). x, F2). Device according to claim 119 or 120, characterized in that the first and the second deformation area (82, 84) are arranged successively in the extension direction of the holding arm (30). Device according to any one of claims 40 to 121, characterized in that each deformation sensor (172, 174, 176, 178) is connected to the associated reference deformation sensor (182, 184, 186, 188) in a Wheatstone bridge (212, 214, 216, 218). Device according to one of claims 40 to 122, characterized in that the evaluation unit (230) has a processor (234) which transforms the values ​​corresponding to the deformations in the deformation-affected areas (152, 154, 156, 158) into the corresponding values ​​(WFx, WFY, WFZ) of three forces (F) acting transversely, in particular perpendicularly, to each other in spatial directions, using transformation values ​​determined and stored in a memory (236) by means of a calibration in a memory. x, F y , F2) is converted to the coupling element (40). Device according to one of claims 40 to 122, characterized in that two of the forces (Fx, Fz) run parallel to, in particular in, the longitudinal median plane (18) of the holding arm (30), but transversely, in particular perpendicularly, to each other, and that the third force (F y) runs transversely, in particular perpendicularly, to the longitudinal median plane (18) of the retaining arm (30). Device according to claim 123 or 124, characterized in that transformation values ​​for force combinations acting on the coupling element (40) in different octants are stored in the memory (236). Device according to one of claims 40 to 125, characterized in that the evaluation unit (230) acquires values ​​from deformation sensors (172, 174, 176, 178) and in particular reference deformation sensors (182, 184, 186, 188) for determining the deformations. Device according to claim 126, characterized in that the evaluation unit (230) acquires values ​​from at least one temperature sensor (252, 254, 256, 258) for functional testing of the reference deformation sensors (182, 184, 186, 188). Device according to claim 127, characterized in that the evaluation unit (230) acquires values ​​from a temperature sensor assigned to each respective reference deformation sensor. Device according to any one of claims 40 to 128, characterized in that the holding arm (30) carries the coupling element (40) at its second end (34). Device according to claim 129, characterized in that the holding arm (30) and the coupling element (40) form a single, continuous part. Device according to claim 129 or 130, characterized in that the holding arm (30) is designed as a ball neck and carries the coupling element (40) comprising a coupling ball (43) at its second end (34). Device according to any one of claims 40 to 131, characterized in that the holding arm (30') comprises a receiving body (31') designed for the releasable reception of the coupling element (40').Device according to claim 132, characterized in that the receiving body (31') has an insertion recess (33') which is accessible through an insertion opening (35'). Device according to claim 132 or 133, characterized in that the coupling element (40') comprises a support arm (42'). Device according to any one of claims 132 to 134, characterized in that the support arm (42') can be inserted into the insertion recess (33') and fixed therein by means of an insertion section (45'). Device according to one of claims 132 to 135, characterized in that the support arm (42') carries a coupling ball (43). Device according to claim 135 or 136, characterized in that the insertion section (45') is received transversely in an insertion direction (E) in a form-fitting manner in the insertion receptacle (33') and is fixed in the insertion direction in the functional state by a form-locking element (41).Device according to the preamble of claim 40 or according to any one of claims 40 to 137, characterized in that the holding arm (30) is provided with at least three deformation sensors (172, 174, 176, 178) which react, in particular, in different ways to three forces acting on the coupling element (40) in spatial directions transverse to each other, and that the at least three deformation sensors (172, 174, 176, 178) provide sensor values ​​(M) from which at least one force component acting on the coupling element (40) is determined by means of an evaluation unit (270). Device according to any one of claims 40 to 138, characterized in that the evaluation unit (230) determines at least one of the values ​​(WFx, WF). y, WFz) of its force component extending in the spatial directions (x, y, z). Device according to one of claims 40 to 139, characterized in that the evaluation unit (270) determines the value (WFz) of its force component extending in the direction of gravity (Z). Device according to one of claims 40 to 140, characterized in that the evaluation unit (230) determines the value (F x ) of its force component running in the direction of travel of the motor vehicle (10). Device according to one of claims 40 to 141, characterized in that the evaluation unit (230) displays the value (F y ) of their force component running transversely, in particular perpendicularly, to a vertical longitudinal mean plane (18).

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