Sensor device with overload protection for a support load measuring device, support load measuring device and system

Abstract

Sensor device (12) for a support load measuring device (10) of a vehicle trailer, wherein the sensor device (12) is designed to detect a mechanical support load acting on the support load measuring device (10) in a force path, wherein the sensor device (12) comprises a support element (28) of the support load and a sensor unit (26), wherein the sensor unit (26) has at least one sensor carrier (30) which is elastically deformable, in particular bendable, at least in sections by the support element (28) for detecting the support load, characterized in that a maximum deformation, in particular bending angle, of the sensor carrier (30) is mechanically limited by a stop element (44), so that an overload protection is formed.

Description

[0001] The invention relates to a sensor device for a support load measuring device of a vehicle trailer, wherein the sensor device is designed to detect a mechanical support load acting on the support load measuring device in a force path, wherein the sensor device comprises a support element of the support load and a sensor unit, wherein the sensor unit has at least one sensor carrier which is elastically deformable, in particular bendable, by the support element for detecting the support load.

[0002] In addition, the invention relates to a support load measuring device with such a sensor device.

[0003] Furthermore, the invention relates to a system comprising the support load measuring device and a holding device for receiving the support load measuring device. STATE OF THE ART

[0004] The tongue load is defined as the force acting on the towing vehicle's towing device for trailers with a short axle spacing (e.g., single-axle car trailers or trailers with an axle spacing of less than one meter, semi-trailers, and center-axle trailers). Manufacturers of trailers and towing vehicles specify maximum permissible tongue loads. The actual tongue load of the trailer must not exceed the maximum permissible tongue load of the towing vehicle. As a rule, tongue loads for car trailers can range from 50 to 150 kilograms, and for agricultural equipment and trucks, the maximum permissible tongue load is 2 tons.

[0005] According to StVZO §§ 42 and 44, the law stipulates a minimum tongue load of 4% of the unladen weight of the trailer for car combinations. To achieve this, the total load of the trailer can be distributed in such a way that a tongue load within the permissible range can be achieved. The decisive factor is the center of gravity, i.e., the distance between the center of gravity or load application point of the trailer and the wheel contact point, which can be calculated mathematically. To achieve a sufficient tongue load in the case of an empty trailer, the axle is usually mounted behind its center of gravity.

[0006] Two extreme cases must be distinguished when it comes to tongue loads: If the tongue load is too high, it can lead to excessive loading of the towing vehicle's rear axles, improper relief of the front axles, and excessive stress on the towing device and mounting points. Furthermore, an excessive tongue load on the trailer can lead to improper loading of the ball coupling or improper loading of the drawbar, with the risk of breakage. On the other hand, an insufficient tongue load on the towing vehicle can lead to dangerous relief of the rear axle, since the rear axle is usually also the drive axle, and can lead to increased load on the front axle.At the same time, an insufficient tongue weight on the trailer leads to excessive loading on the rear axle and excessive tensile stress on the ball coupling and drawbar, which in turn poses a risk of breakage due to excessive tensile stress. Maximum permissible tongue weights are usually printed or embossed on every trailer coupling.

[0007] To ensure the correct use of the trailer, it is important to ensure that the tongue load is within the specified range when the trailer is used as intended. Accordingly, the tongue load must be checked before putting the trailer into operation.

[0008] The actual vertical load of a trailer hitch can be determined using so-called vertical load scales, which are used to measure vertical loads. Such vertical load scales are often designed as spring scales and are installed in the towing eye of a trailer hitch for correct use. However, a widely used measurement using a mechanical scale and the nose wheel of a trailer can result in measurement errors of up to 15% due to the leverage exerted by the drawbar.

[0009] In addition to mechanical support load scales, electronic support load scales are also known from the prior art, for example, from the applicant's EP 2 280 263 B1. The support load scale has a sensor device by means of which the acting support load can be detected and evaluated in conjunction with appropriate evaluation electronics, so that a user can be provided with reliable information as to whether the current support load lies within the prescribed range. The sensor device can be designed as a mechanically operating sensor device, wherein, using a strain gauge, the support load can be determined by elastic deformation of a sensor carrier carrying the strain gauge.The sensor carrier is supported on a support element, with the sensor carrier and support element being designed and arranged relative to each other in such a way that when the support load acts on the support load scale, the support element is pressed against the sensor carrier, bending or deforming it accordingly, at least in sections. The support load can be determined based on the resulting deformation of the strain gauge arranged on the sensor carrier.

[0010] The problem here, however, is that the known tongue load scale is only designed for a certain maximum tongue load. Due to the material (thickness), the sensor carrier can only be elastically deformed up to a certain degree. If this limit is exceeded, the sensor carrier may become plastically deformed due to excessive deformation, in particular permanently deformed or break, thus damaging the sensor device or the tongue load scale, in particular irreparably, and thus no longer functioning. Repair or replacement is generally complex and expensive. Therefore, with the known tongue load scale, it is necessary for the user to always be careful not to overload the tongue load scale, i.e. to always ensure that the maximum tongue load for which the tongue load scale is designed is not exceeded. This significantly reduces user comfort.

[0011] Understandably, however, despite the utmost care, it is not always possible in practice to ensure that the support load scale is not subjected to excessive load. It is therefore quite common for the support load to be completely underestimated even before the first measurement. During the actual measurement, a support load scale that is not suitable for this support load is then inadvertently used, which subsequently becomes damaged due to overload. Therefore, there is a great need for safety measures to prevent accidental damage to the support load scale due to overload, i.e., overload protection.

[0012] The object of the invention is therefore to provide a sensor device for support load measuring devices which is improved with regard to the above problem and which has reliable overload protection.

[0013] This object is achieved by a sensor device, a support load measuring device, and a system according to the independent claims. Advantageous embodiments of the invention are the subject of the dependent claims. DISCLOSURE OF THE INVENTION

[0014] The invention is based on a sensor device for a support load measuring device of a vehicle trailer. The sensor device is designed to detect a mechanical support load acting on the support load measuring device along a force path. The sensor device comprises a support element for the support load and a sensor unit, wherein the sensor unit has at least one sensor carrier that is elastically deformable, in particular bendable, at least in sections by the support element for detecting the support load.

[0015] According to the invention, a maximum deformation, in particular the bending angle, of the sensor carrier is mechanically limited by a stop element, thus forming overload protection. The sensor carrier is deformable in at least one spatial direction for measuring the support load, wherein this spatial direction runs opposite to the force path. The force path is generally defined by a ball-head-shaped trailer, referred to as a ball head, which is modeled on a typical trailer coupling, up to a standing area of ​​a base of the support load measuring device. The stop element limits the deformation of the sensor carrier at least in this spatial direction. The stop element is fixed in position and designed to be unbendable or offers sufficient mechanical resistance to limit the deformation of the sensor carrier.This advantageously and reliably ensures that the sensor carrier cannot be excessively deformed, which could result in breakage, even in the event of an overload. Thus, the stop element effectively prevents damage to the sensor carrier in the event of an overload, thus providing effective overload protection.

[0016] According to a preferred development, the sensor unit can comprise the sensor carrier, a sensor element, and a sensor base. The sensor element is designed as a strain gauge, the sensor carrier is designed in the manner of a spring tongue with a frame section and a tongue section that accommodates the strain gauge and is deformable, in particular bendable, relative to the frame section. The tongue section is supported on the sensor base arranged on the support element. This advantageously provides a structurally simple and mechanically robust design of the sensor unit, which is also particularly cost-effective to manufacture.

[0017] In particular, the sensor carrier has two, preferably parallel, tongue sections. In particular, the tongue section has a receiving area for the strain gauge. The receiving area is preferably designed as a receiving recess that is at least partially complementary to the strain gauge, into which the strain gauge can be inserted. In particular, the strain gauge is glued to the tongue section. The sensor base and the tongue section can have complementary grooves / protrusions that engage with each other at least when the support load is detected, i.e., the deformation of the sensor carrier by the support element. This advantageously provides a mechanical guide that ensures reliable and precise force transmission without slipping.

[0018] According to a preferred development, the stop element can be designed as a stop plate arranged at a predefined or predefinable deformation distance from the sensor carrier. The maximum deformation of the sensor carrier is limited by the deformation distance. Accordingly, the overload protection, i.e., the point at which it takes effect, can be determined by the deformation distance. The shape, material, and thickness of the stop plate can be selected depending on the design of the sensor carrier. Advantageously, the overload protection is thus particularly simple in design, robust and resilient, and thus cost-effective.

[0019] According to a preferred development, it can be provided that the deformation distance of the stop plate from the sensor carrier is adjustable. In other words, the deformation distance of the stop plate from the sensor carrier can be varied. Accordingly, the arrangement position of the stop plate is flexible or changeable. Accordingly, the overload protection can also be flexibly adjusted. Advantageously, the possibility of varying the overload protection allows the sensor device to be adapted to the individual usage requirements of the respective application.

[0020] According to a preferred development, the sensor unit, the support element, and / or the stop element can be interchangeable. In particular, the sensor carrier, sensor element, and / or sensor base are interchangeable. The components of the sensor device can thus be exchanged, replaced, and / or varied as needed. This advantageously enables simple maintenance and repair of the sensor device, as well as flexible adaptation to the individual requirements of the respective application, so that the sensor device offers particularly high flexibility with regard to potential application possibilities.

[0021] In a subordinate aspect, the invention comprises a support load measuring device for an uncoupled vehicle trailer, wherein the support load measuring device can be temporarily coupled to a trailer device of the vehicle trailer and is designed to measure a support load acting on the support load measuring device along a force path between the trailer device and the earth's surface. The support load measuring device comprises - at least one sensor device arranged in the force path between the towing device and the earth's surface for measuring at least the support load transmitted via the towing device; - an evaluation electronics unit in electrical contact with the sensor device for evaluating a support load measurement value; - at least one display unit for indicating the support load; - a power supply unit for supplying the evaluation electronics unit with electrical energy; and - a weatherproof sensor housing that comprises at least the sensor device, the evaluation electronics unit and the power supply unit;

[0022] The support load measuring device is characterized by the sensor device being designed according to the invention as described above. This results in the advantages already mentioned above.

[0023] According to a preferred development, the support load measuring device can be provided with at least one charging interface, in particular a USB port, preferably arranged in the sensor housing, for charging a power storage device of the power supply unit, in particular a battery. The charging interface is accessible to the user from outside the sensor housing. This advantageously provides a reliable power supply to ensure the operability of the support load measuring device. The rechargeable power storage device particularly advantageously allows for transportable or mobile use, since no stationary power source is required.

[0024] According to a preferred development, it can be provided that the charging interface is arranged in the sensor housing in such a way that it is accessible to a user, such that the charging interface faces the earth's surface during intended use of the support load measuring device and / or that a cover element, in particular a lid, is included for the charging interface. This orientation ensures that during intended use in areas unprotected from the weather, especially rain, no water or dirt gets into the charging interface, as the water or dirt particles flow downwards. This protection is further improved by the cover element, as it reliably seals the charging interface. Advantageously, the charging interface is thereby effectively protected against moisture and dirt and the associated potential functional impairment.

[0025] In a further subordinate aspect, the invention comprises a system comprising the above-described inventive support load measuring device and a holding device that can be fastened to a holding surface of a vehicle trailer or towing vehicle, in particular the trunk floor or vertical side wall of the towing vehicle or the side wall of the vehicle trailer. The holding device is designed to at least temporarily receive the support load measuring device, preferably in a force-fitting or form-fitting manner, and to store it on the holding surface. The holding device can be fastened to a variety of suitable surfaces, for example by gluing or screwing. The support load measuring device can then be easily accommodated in the holding device for transport or storage purposes. Accordingly, the holding surface is preferably located at a location where the support load measuring device can be arranged in a protected manner without causing interference.This advantageously provides a convenient way to store and transport the support load measuring device.

[0026] According to a preferred development, the holding device can be designed as a holding shell, wherein the holding shell has a recess for a charging interface of the support load measuring device in a shell section associated with the sensor housing, so that when the support load measuring device is stored, the charging interface can be used to charge the support load measuring device. Advantageously, the support load measuring device can thus be conveniently charged to ensure its operability during storage, so that it is reliably ready for use when removed from the holding device and intended for use. DRAWINGS

[0027] Further advantages will become apparent from the accompanying drawing description. The drawings illustrate exemplary embodiments of the invention. The drawings, the description, and the claims contain numerous features in combination. Those skilled in the art will also expediently consider the features individually and combine them into useful further combinations.

[0028] They show: Fig. 1A to 1D A perspective view of an advantageous support load measuring device from different angles, Fig. 2A and Fig. 2B a cross-sectional view of the support load measuring device from a different angle Fig. 3A to 3D show various views of an advantageous sensor device of the support load measuring device, Fig. 4 an exploded view of the sensor device, and Fig. 5A to 5D different views of a holding device for the support load measuring device,

[0029] In the figures, similar elements are numbered with the same reference numerals. The figures are merely examples and are not to be construed as limiting.

[0030] Fig. 1A to 1D show various views of an advantageous support load measuring device 10. Each of the figures shows the support load measuring device 10 from a different angle. The support load measuring device 10 serves to measure a support load generated by a vehicle trailer (not shown in detail here for reasons of clarity). For this purpose, the support load measuring device 10 can be temporarily coupled to a trailer device of the vehicle trailer when the vehicle trailer is uncoupled. In this context, the support load measuring device 10 is designed and can be coupled to the trailer device in such a way that a support load acting on the support load measuring device 10 along a force path between a ball head 52 of the trailer device and a support load flow 54 on the earth's surface can be measured.

[0031] The design and operation of the support load measuring device 10 are generally known, so only the essential aspects will be discussed below. For further details, reference is made to the applicant's aforementioned application EP 2 280 263 B1, wherein the present support load measuring device 10 represents an improvement on the support load measuring device disclosed therein.

[0032] The essential components of the support load measuring device 10 are a sensor device 12, an evaluation electronics unit 14, a display unit 16, a power supply unit 18, and a sensor housing 20. The sensor device 10 is arranged in the force path between a ball head 52 of the trailer coupling and a support load foot 54 of the earth's surface and serves to measure or detect the support load. Further details regarding the sensor device 12 will be discussed in more detail later. The evaluation electronics unit 14 is in electrical contact with the sensor device 12 and is designed to evaluate the signals detected by the sensor device 12 and thereby calculate the support load or a corresponding support load measured value between the ball head 52 and the support load foot 54. The display unit 16 serves to display the support load or the support load measured value; the display unit 16 can be an LED display or similar device.The power supply unit 18 supplies at least the evaluation electronics unit 14, and in this case also the display unit 16, with electrical energy, thus ensuring the operability of the support load measuring device 10. In this respect, the present support load measuring device 10 is an electrically operable support load measuring device. The sensor device 12, evaluation electronics unit 14, display unit 16, and power supply unit 18 are enclosed in the sensor housing 20, which is designed to be weatherproof. The sensor housing 20 serves primarily to protect and, at least in part, also to mechanically connect or hold together the remaining components of the support load measuring device 10.

[0033] In the present case, the support load measuring device 10 comprises a charging interface 22 as a further component, which is particularly in the Fig. 1C and Fig. 1D. According to the present exemplary embodiment, the charging interface 22 is designed as a USB port. The charging interface 22 serves to charge a power storage device of the power supply unit 18 (not shown in detail here for reasons of clarity). In particular, the power storage device is a rechargeable battery. Thus, the support load measuring device 10 can be operated in a mobile manner or independently of a stationary power supply, for example, the power grid. In other words, the support load measuring device 10 or its power storage device can be conveniently charged with electrical energy using the charging interface 22 and then used in a mobile manner.

[0034] As in Fig. 1C and Fig. 1D, the charging interface 22 is arranged in the sensor housing 20 in such a way that it is accessible to the user and faces the earth's surface when the support load measuring device 10 is used as intended. In simple terms, the charging interface 22 is oriented downwards or towards the earth's surface. Advantageously, the charging interface 22 is thus arranged in a weather-protected manner. For example, the corresponding arrangement ensures that when the support load measuring device 10 is used in the rain, water flowing down the support load measuring device 10 or the sensor housing 20 does not penetrate into the interior of the charging interface 22 and thus into the interior of the support load measuring device 10. The orientation of the charging interface 22 also minimizes the risk of dust particles penetrating the charging interface 22 due to wind. Optionally, a Fig. 1C and Fig. 1D, a cover element 24 for the charging interface 22 may be included. Using the cover element 24, for example a lid, the charging interface 22 can be securely closed when not in use. This further improves the protection of the charging interface 22 from the elements.

[0035] Fig. 2A and Fig. 2B each show a cross-section through the support load measuring device 10 in a side view. As in the highlighted sections of the Fig. 2A and Fig. As can be seen in Figure 2B, the sensor device 12 is arranged in the upper region of the sensor housing 20. If the support load measuring device 10 is loaded with the support load by the vehicle trailer during normal operation, this can be detected by the sensor device 12, as already discussed above.

[0036] Fig. 3A to 3D show various views of the sensor device 12. The sensor device 12 is embodied as an electromechanical sensor device 12. The support load is thus detected by means of a combination of mechanical and electrical signals. The sensor device 12 comprises a sensor unit 26 and a cooperating support element 28. The sensor unit 26 comprises a sensor carrier 30, a sensor element 32, and a sensor base 34. The sensor carrier 30 is designed like a spring tongue and comprises a frame section 36 and at least one tongue section 38. The sensor element 32 is embodied as a strain gauge and is received or mounted on the tongue section 38, as shown in Fig. 1C is indicated by dashed lines. The tongue portion 38 is deformable relative to the frame portion 36 and is supported on the sensor base 34, which in turn is arranged on the support element 28.

[0037] In order to detect the support load, the sensor carrier 30 can be mechanically and elastically deformed by the support element 28. More precisely, when a support load is applied, the support element 28 with the sensor base 34 arranged thereon presses against the tongue section 38 of the sensor carrier 30, whereby the tongue section 38 is elastically deformed or bent relative to the frame section 36. As the tongue section 38 deforms, the sensor element 32 or the strain gauge received thereon is also deformed. This mechanical deformation is converted into electrical signals by the sensor element 32 or the strain gauge. The electrical signals depend on the degree of deformation, which in turn is determined by the magnitude of the support load acting on the sensor device 12 or the support load measuring device 10. Thus, the sensor device 12 orof its corresponding components, the support load acting on the support load measuring device 10 can be determined based on the deformation of the sensor carrier 30 with the sensor element 32 arranged thereon.

[0038] As particularly in Fig. 3A and Fig. As can be clearly seen in Figure 3B, the sensor carrier 30, more precisely its tongue section 38, and the sensor base 34 can have mutually complementary projections 40 and grooves 42. In the present case, the sensor carrier 30 has two tongue sections 38, each with a groove 42. The sensor base 34, in turn, has two corresponding projections 40, each associated with a groove 42. When the sensor device 12 or support load measuring device 10 is used as intended, the projections 40 and grooves 42 engage with each other when the support element 28 is pressed against the sensor unit 26. More precisely, with the displacement of the support element 28 in the direction of the sensor carrier 30, the projections 40 of the sensor base 34 are inserted or inserted into the grooves 42 of the tongue sections 38, so that from then on the tongue sections 38 and the sensor base 34 are positively connected to one another.This provides a guiding function that reliably prevents the tongue sections 38 from slipping off the sensor base 34 and the associated influence on the measurement. Furthermore, the guiding function ensures a controlled and uniform deformation of the tongue sections 38 and thus an accurate measurement.

[0039] Due to the material type and thickness of the sensor unit 26, in particular the tongue sections 38, the elastic deformation of the tongue sections 38 is mechanically limited. Excessive deformation of the tongue sections 38 can break, rendering the sensor device 12 inoperable, particularly irreparably damaged. Therefore, there is a risk that, during the intended use of the support load measuring device 10, it may be subjected to excessive loads, for example, due to carelessness or ignorance on the part of the user. This means that the support load acting on the support load measuring device 10 may be too great for the mechanical load-bearing capacity of the sensor device 12.

[0040] To reliably prevent such damage due to excessive loading, overload protection is advantageously provided in the present sensor device 12 or support load measuring device 10. In this case, the overload protection is formed by a stop element 44, which mechanically limits the maximum deformation, in particular the bending angle, of the sensor carrier 30 or the tongue sections 38.

[0041] Fig. 4 shows a side view of an exploded view of the sensor device 12. The stop element 44 is designed as a stop plate and is arranged at a predefined or predefinable deformation distance V from the sensor carrier 30. The deformation distance V thus corresponds to the maximum possible deformation of the sensor carrier 30 or the tongue sections 38. If a support load acts on the support load measuring device 10 that would lead to a deformation of the tongue sections 38 that is greater than the deformation distance V and thus to their breakage, the deformation is limited by the stop element 44 and thus breakage is reliably prevented. This is because, instead of being excessively deformed, the tongue sections 38 simply abut the stop element 44 under excessive load.The stop element 44 is designed in terms of material technology, i.e. in particular with regard to material type and material thickness, such that it offers sufficient mechanical resistance for the tongue sections 38.

[0042] As in Fig. As can be further seen in Figure 4, the arrangement of the sensor base 34 on the support element 28 creates a safety distance S between the support element 28 and the sensor carrier 30. The safety distance S ensures that when the support element 28 is pressed against the sensor carrier 30, only the tongue sections 38 are deformed as intended, while deformation of the remaining sections of the sensor carrier 30 is avoided. Thus, the functionality of the sensor unit 12 is reliably ensured by the above-described arrangement and spacing of the stop element 44, the sensor carrier 30, and the support element 28.

[0043] Optionally, it can be provided that the deformation distance V from the stop element 44 to the sensor carrier 30 is adjustable. This allows the maximum possible deformation of the tongue sections 38 to be set, so that, at least within a certain range, the sensor device 12 or support load measuring device 10 can be adapted to the individual requirements of the respective application. In other words, the maximum possible detectable support load can be adjusted by varying the deformation distance V, at least within the range within which the deformation of the tongue sections 38 does not lead to their breakage. Optionally, it can also be provided that the sensor unit 26, the support element 28 and / or the stop element 44 are replaceable. Thus, the components of the sensor unit 26, i.e. sensor carrier 30, sensor element 22 and sensor base 34, can also be replaceable. This enables uncomplicated maintenance and / orRepair of the sensor unit 12 in case of damage as well as adaptation of the mechanical properties of the sensor device 12 to the respective application by simply replacing the individual components.

[0044] Fig. 5A to 5D show various perspective views of an advantageous holding device 46 for the support load measuring device 10. The support load measuring device 10 and the holding device 46 together form a system.

[0045] The holding device 46 can be fastened to a holding surface of the vehicle trailer or a towing vehicle. For example, the holding device 46 can be fastened to a trunk floor or to a vertical side wall of the towing vehicle or to a side wall of the vehicle trailer. The fastening can be positively, non-positively, and / or materially connected, for example by screwing or gluing. The holding device 46 is designed to at least temporarily accommodate the support load measuring device 10 in a non-positively or positively connected manner, such that the support load measuring device 10 can be supported on the holding surface by means of the holding device 46 when the holding device 46 is fastened to the holding surface as described above. In other words, the support load measuring device 10 can be supported on the holding surface by being received in the holding device 46 fastened to the holding surface.

[0046] As in the Fig.5A to 5D, the holding device 46 is designed as a holding shell. In this case, the holding shell has a recess 50 for the charging interface 22 on a shell section 48 assigned to the sensor housing 20. In this respect, the support load measuring device 10 can be received in the holding device 46 such that, in the received state, the charging interface 22 is aligned with the recess 50 and is thus accessible to the user. This advantageously ensures that, when the support load measuring device 10 is in the stored state, the charging interface 22 can be used to charge the support load measuring device 10. In other words, the support load measuring device 10 can be charged in the stored state by simply accessing the charging interface 22 through the recess 50.As a result, the support load measuring device 10 can be conveniently charged in the stored and therefore not used state and can then be charged and thus removed from the holding device 46 in an operational state. List of reference symbols 10 Support load measuring device 12 Sensor device 14 Evaluation electronics unit 16 display unit 18 Power supply unit 20 sensor housings 22 Charging interface 24 Cover element 26 Sensor unit 28 Support element 30 sensor carriers 32 sensor element 34 Sensor base 36 frame section 38 tongue section 40 lead 42 grooves 44 Stop element 46 Holding device 48 shell section 50 recess 52 ball head 54 Support load foot S Safety distance V Deformation distance QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] EP 2 280 263 B1 [0009, 0031]

Claims

[1] Sensor device (12) for a support load measuring device (10) of a vehicle trailer, wherein the sensor device (12) is designed to detect a mechanical support load acting on the support load measuring device (10) in a force path, wherein the sensor device (12) comprises a support element (28) of the support load and a sensor unit (26), wherein the sensor unit (26) has at least one sensor carrier (30) which is elastically deformable, in particular bendable, at least in sections by the support element (28) for detecting the support load, characterized by that a maximum deformation, in particular bending angle, of the sensor carrier (30) is mechanically limited by a stop element (44), so that an overload protection is formed. [2] Sensor device according to claim 1, characterized byin that the sensor unit (26) comprises the sensor carrier (30), a sensor element (32), and a sensor base (34), wherein the sensor element (32) is designed as a strain gauge, the sensor carrier (30) is designed like a spring tongue with a frame section (36) and a tongue section (38) which receives the strain gauge and is deformable, in particular bendable, relative to the frame section (36), wherein the tongue section (38) is supported on the sensor base (34) arranged on the support element (28). [3] Sensor device according to one of the preceding claims, characterized by that the stop element (44) is designed as a stop plate which is arranged at a predefined or predefinable deformation distance (V) from the sensor carrier (30). [4] Sensor device according to claim 3, characterized by that the deformation distance (V) of the stop plate to the sensor carrier (30) is adjustable. [5] Sensor device according to one of the preceding claims, characterized by that the sensor unit (26), the support element (28) and / or the stop element (44) are interchangeable. [6] Support load measuring device (10) for an uncoupled vehicle trailer, wherein the support load measuring device (10) can be temporarily coupled to a trailer device of the vehicle trailer and is designed to measure a support load acting on the support load measuring device (10) along a force path between the trailer device and the earth's surface, comprising - at least one sensor device (12) arranged in the force path between the trailer coupling and the earth's surface for measuring at least the support load transmitted via the trailer coupling; - an evaluation electronics unit (14) in electrical contact with the sensor device (12) for evaluating a support load measurement value; - at least one display unit (16) for displaying the support load; - a power supply unit (18) for supplying the evaluation electronics unit (14) with electrical energy; - a weatherproof sensor housing (20) comprising at least the sensor device (12), the evaluation electronics unit (14) and the power supply unit (18); characterized by a design of the sensor device (12) according to one of claims 1 to 5. [7] Support load measuring device according to claim 6, characterized by that the support load measuring device (10) has at least one charging interface (22), in particular a USB port, preferably arranged in the sensor housing (20), for charging a power storage device of the power supply unit (18), in particular a battery. [8] Support load measuring device according to claim 7, characterized bythat the charging interface (22) is arranged in the sensor housing (20) in such a way that it is accessible to a user, that the charging interface (22) faces the earth's surface when the support load measuring device (10) is used as intended and / or that a covering element (24), in particular a cover, is included for the charging interface (22). [9] System comprising a support load measuring device (10) according to one of claims 6 to 8 and a holding device (46) which can be fastened to a holding surface of a vehicle trailer or towing vehicle, in particular the trunk floor or vertical side wall of the towing vehicle or side wall of the vehicle trailer, wherein the holding device (46) is designed to at least temporarily receive the support load measuring device (10), preferably in a force-fitting or form-fitting manner, and to mount it on the holding surface. [10] System according to claim 9, characterized bythat the holding device (46) is designed as a holding shell, wherein the holding shell has a recess (50) for a charging interface (22) of the support load measuring device (10) in a shell section (48) assigned to the sensor housing (20), so that in the stored state of the support load measuring device (10) the charging interface (22) can be used to charge the support load measuring device (10).

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