trailer hitch

Abstract

Trailer coupling for a roadworthy vehicle trailer (2), wherein the trailer coupling (1) comprises a coupling housing (13) with a coupling receptacle (17) for a towing vehicle-side coupling element (12), a coupling mechanism (14) designed to open and close the trailer coupling (1) and a preferably pivotable operating element (22), characterized in that the trailer coupling (1) - a mechanical coupling indicator (33) which detects and indicates correct coupling of the trailer coupling (1) to a coupling element (12) on the towing vehicle side, wherein the mechanical coupling indicator (33) has a movable, preferably pin-like, indicator element (34) with an outer indicator head (35), which is arranged in a receiving opening (38) on the coupling housing (13) and can be displaced from an initial position (36) into a visually recognizable indicator position (37) on the coupling housing (13) upon correct coupling of the coupling element (12) on the towing vehicle side, wherein - the trailer coupling (1) additionally comprises a sensory detection device (41) with a sensor unit (42) which detects correct coupling of the trailer coupling (1) to the coupling element (12) on the towing vehicle side, wherein the sensor unit (42) is assigned to the display element (34) and detects and signals its displacement and / or its leaving the initial position (36) and / or its assuming the display position (37).

Description

The invention relates to a trailer coupling having the features in the preamble of claim 1.Such trailer couplings for a road-borne vehicle trailer are known from practice. The trailer coupling comprises a coupling housing with a coupling receptacle for a coupling element of a towing vehicle. It further comprises a coupling mechanism which is designed for opening and closing the trailer coupling and a preferably pivotable operating element.DE 20 2009 005 185 U1, which is incorporated by reference herein in its entirety, in a maneuvering drive for trailers and its safe function, shows a trailer coupling having an unlit coupling lever and a sensor system for the coupling situation. The sensor system can comprise a position detector on the clutch lever or a contact detector located in the clutch shell, which detects an electrical contact with a metallic clutch ball immersed in the clutch shell by means of a sensor. Such an electrical contact sensor can also be arranged in a non-illustrated snap-in indicator according to DE 94 12 514 U1 and electrically sense the contact with the coupling ball.DE 10 2020 119 506 A1 discloses a trailer coupling with an unlit coupling lever and a locking indicator with an extendable marking pin. It also teaches a camera arranged on the vehicle body and far away from the trailer coupling, which detects a pivot position of the coupling lever assumed during the correct coupling or, if applicable, an extended position of the marking pin optically from the outside and with a view obliquely from above onto the trailer coupling.German patent document DE 10 2022 123 784 A1, which is foreign to the species, relates to an anti-theft device on the towing vehicle, which prevents an unauthorized decoupling of a trailer or rear load carrier from the hitch ball of the towing vehicle. For this purpose, spring-loaded locking pins that can be actuated by an electromagnet are arranged in the coupling ball. A light element on the coupling rod of the towing vehicle indicates the position of the locking pins, which cannot be seen from the outside in the coupling position.DE 11 2022 005 586 T5, likewise of the same type, relates to a contactless sensor arrangement for a fifth wheel of a semi-trailer, wherein the engagement position of a king pin of the semi-trailer on the fifth wheel plate of the truck is detected.It is an object of the present invention to show a trailer coupling which is improved with regard to operability.The invention achieves this object with the features in the independent claims.According to a first aspect of the invention, the claimed trailer coupling comprises a mechanical coupling indicator and additionally a sensory detection device. A correct coupling of the trailer coupling to a coupling element on the towing vehicle side and the assumption of the coupling position can thereby be detected both mechanically and sensorially. The ability to identify a correct coupling is improved for the operator.In addition, the recognition safety for the operator is increased.When the coupling is correctly coupled, the coupling element on the towing vehicle side, e.g. a coupling ball, is received in a coupling receptacle of the trailer coupling, e.g. a ball receptacle, and is held there in a form-fitting manner by means of a coupling mechanism.The mechanical coupling display comprises a movable display element which is preferably designed in the manner of a pin and has an outer display head. This is preferably arranged at the free outer end of the display element. It can have a widened shape compared to a preferably pin-shaped and straight shaft of the display element. The display element is arranged in a receiving opening on the clutch housing and, in the event of a correct coupling, can be displaced by the coupling element on the towing vehicle side from a starting position into an optically recognizable display position on the clutch housing. The preferably pin-like display element can project outwardly from the coupling housing, for example, with the display head, wherein a color marking can possibly become visible and can additionally signal the display position.The sensor detection device has a sensor unit which detects the correct coupling. The sensor unit can be assigned to the display element and can detect and signal its displacement and / or its departure from the starting position and / or its assumption of the display position. The sensor detection device can comprise further components explained below.In a second and independent aspect of the invention, the previously known trailer coupling can have a lighting device which is arranged on said operating element. The preferably pivotable operating element can be designed as a clutch lever for actuating the clutch mechanism or as a friction brake lever for actuating a friction brake explained below. The operating element can also have a different kinematic mechanism and can be displaceable, for example.The two aspects of the invention can be used individually and independently of each other. In a preferred embodiment, the trailer coupling comprises both aspects of the invention. The trailer coupling according to the invention can be mounted on road-engaging vehicle trailers in the initial equipment. It can also be replaced by an existing conventional trailer coupling by means of the changeover or retrofitting.The trailer coupling advantageously comprises an actuatable friction brake which is provided and designed for cooperation with the coupling element on the towing vehicle side in the coupling position. Rolling movements of the vehicle trailer can be damped by the friction brake. The roll movements may include sideslip movements about a vertical axis and also roll movements about a longitudinal axis of the vehicle trailer.Said friction brake lever can be designed for manual operation of such a friction brake. The trailer clutch may include both the clutch lever and the friction brake lever. In another variant, the claimed trailer coupling can be designed without a friction brake.In an advantageous embodiment, the friction brake can have spring-loaded friction plungers which can be pressed by the preferably pivotable friction brake lever by means of a lifting bearing and a plunger actuation onto the coupling element on the towing vehicle side with frictional engagement. The plunger actuation can be designed, for example, as a slotted guide, which converts the lever movement into a pressing movement of the friction plungers. The friction brake can comprise further friction elements, for example one or more friction shells arranged in the clutch receptacle. These can optionally be adjusted in another way and brought into frictional and pressing contact with the towing vehicle-side coupling element, e.g. the coupling ball. The friction brake lever can comprise pivotable lever arms connected to a lever mounting and a lever bridge arranged between the lever arms.The sensor unit of the sensory detection device can be arranged at the outer end region of the receiving opening in the coupling housing. The outer end region is spaced apart from the coupling element on the towing vehicle side. The sensor unit is protected at this outer end region from environmental influences, in particular from dirt or abrasion, which can arise in the region of the coupling receptacle and of the coupling element on the towing vehicle side. This is advantageous for the functional and detection safety of the sensor unit.The sensor unit can be designed in different ways. In one embodiment, it can comprise a plurality of interacting sensor elements, for example a Hall sensor and a magnet, which are arranged alternately on the display element, in particular on the display head, and on the receiving opening. The sensor unit can also comprise a preferably sleeve-shaped insert part which can be mounted in the receiving opening and which receives the opening-side sensor element, for example a Hall sensor. This enables a conversion of a display element that may be present in exchange for the display element according to the invention and the sensor unit.In another variant, the sensor unit can comprise a contactless inductive proximity sensor. In a further variant, the sensor unit can comprise a contact switch. The contact switch can be designed, for example, as an end position switch with a temporary contact to the display element. It can also be designed as a slide switch with permanent contact with the display element, wherein the permanent contact is formed, for example, by a wedge guide. This can deflect an outward movement of the display element during its displacement into a sliding movement of the slide switch, wherein the sliding movement can be detected or the assumption of an end position of the slide switch can also be detected. In addition, further variants of the embodiment are possible.The sensory detection device can comprise one or more sensor units. It can also comprise an evaluation unit and an alarm means connected thereto. The sensory detection device can also have a power supply. These components, in particular the evaluation unit and the energy supply, can be coupled to the sensor unit by a signal means. The signal means can be configured, for example, in a wired manner and as a cable. The power supply of its own can be omitted, for example in favor of a power supply on the trailer side or other type of power supply.The sensory detection device can furthermore comprise a wirelessly communicating communication means, which is preferably arranged on the evaluation unit, in particular on a circuit board of the evaluation unit. Via this communication means, the evaluation unit can communicate with a remote control or with another external device.A remote control can serve for operating and / or monitoring other trailer components, for example a maneuvering drive, a stabilizing device or rolling brake, an ABS system, an electric axle, a separate energy supply, in particular a rechargeable battery, the vehicle trailer or the like. The remote control may be a dedicated operation device. The remote control can also be formed by a smartphone, tablet, computer or the like with at least one operating and / or display app.The remote control can comprise at least one display and optionally also input means. A remote control can also be implemented in a towing vehicle.Said alarm means can be designed and function in different ways. It may comprise one or more elements. The alarm means can output a cause-specific alarm, from which the cause of the alarm and possibly also a message for eliminating the cause are communicated to an operator. The cause may include an error that has occurred, e.g., a coupling error. The message can contain a specification of the fault that has occurred and, if necessary, an operating instruction for fault correction. This is particularly advantageous if there are several different possible causes and errors. This can be the case, for example, in a functional expansion of the evaluation unit explained below.The alarm means can have, for example, one or more light elements which are arranged on the trailer coupling, in particular on the preferably pivotable operating element, preferably on the friction brake lever. The light elements can output a cause-specific alarm by selective lighting, flashing, color change, assignment to a inscription or in another way. The alarm means may alternatively or additionally also comprise said communication means and signal an alarm, e.g. via the remote control. An alarm can be emitted optically, for example by the light element or elements and / or a display on the remote control and / or acoustically by a buzzer, loudspeaker or other sound emission means. An alarm can be triggered by the evaluation unit as a function of the evaluated signals of the sensor unit.Said sensory detection device has the advantage that it can indicate the correct or incorrect coupling via the evaluation of the signals of the sensor unit and via the alarm means in addition to the mechanical coupling indication and also in a manner different from the latter. The display or an alarm can be perceived by the operator even in unfavourable environmental and visual conditions, in particular in darkness. In addition, the sensory detection device can independently detect and display a faulty and above all incomplete coupling on the coupling element on the towing vehicle side or signal it by an alarm.In the event of a faulty coupling, for example, the coupling receptacle can only be loosely placed on the coupling element on the towing vehicle side, for example the coupling ball, wherein the preferably pin-like display element is already in contact therewith and displaced a certain distance from its starting position. This departure from the starting position can be detected by the sensor unit and, if appropriate, can already be displayed. If the coupling element on the towing vehicle side then does not enter completely into the coupling receptacle and is locked in the coupling position by the coupling mechanism, the display element does not reach its display position. This can likewise be detected by the sensor unit and detected and displayed or signaled by the evaluation unit as a fault.These indicators and alarms of the sensory detection device can be clearer and better perceptible than just the signaling of the mechanical coupling indicator. The mechanical coupling display and the sensor detection device can thus complement one another in an optimum manner and offer the operator a high level of detection reliability for the correct or incorrect coupling state of the vehicle trailer to the towing vehicle even under adverse environmental conditions. This is particularly true in poor visibility conditions, such as darkness, rain, snow or the like.The trailer coupling can also comprise further advantageous components. It may for example comprise a front cap made of a compressible and shock absorbing material which can be attached to the front side of the coupling housing. The front cap encloses the coupling housing in this region. It has a through-opening for the mechanical coupling indicator. It can also provide an advantageous seal for this purpose.The trailer coupling can furthermore have a sensor system on the coupling housing, which is provided and designed to absorb one or more physical parameters of the vehicle trailer in the trailer combination mode. Such physical parameters can be, for example, force and / or travel and / or acceleration. These parameters can occur, for example, when the towing vehicle is braked and the vehicle trailer runs onto the towing vehicle and can lead to the actuation of a possible run-on brake on the vehicle trailer. On the other hand, these parameters can occur during an acceleration of the towing vehicle and a possibly occurring relative movement of the towing vehicle with respect to the vehicle trailer. The said parameter path can relate to a run-up path during braking or a pull-out path during the subsequent acceleration of the towing vehicle. A ramp-up path can also occur when the towing vehicle and the vehicle trailer are travelling backwards.During said recording, the sensor system can basically record the physical parameters and, if applicable, their size by measurement.The sensor system can be connected to the evaluation unit and, if applicable, to the energy supply and also to the communication means or the alarm means. The sensor system signals reported by the sensor system can be evaluated by the evaluation unit and can be communicated in raw form or in evaluated form by the communication means to a receiver on the vehicle trailer or to an external receiver, for example the said remote control.The recording and evaluation of said physical parameters can serve different purposes. On the one hand, the current mass of the vehicle trailer can be determined by this means, wherein the determination value for the mass can be transmitted to a stabilization device or a rolling brake, an anti-lock brake system or an electric drive and brake device of the vehicle trailer.On the other hand, by bidirectional communication of the sensory detection device, in particular of the evaluation unit, a signal can be transmitted from the stabilization device and / or the anti-lock brake system and / or the electric drive and brake device. The signal can contain, for example, information about the occurrence of rolling phenomena, blocking vehicle wheels, activation of the electric drive and brake device or the like. The sensory detection device, in particular the evaluation unit, can then possibly trigger an alarm. A cause-specific alarm is of particular advantage in this case. The alarm can be displayed, for example, to the driver in the towing vehicle.Furthermore, a further sensor device can be arranged on the vehicle trailer. It can be connected to components of the sensory detection device, e.g. the evaluation unit and optionally the energy supply as well as the communication means. The sensor device can comprise one or more sensors, with which operationally relevant, in particular safety-relevant, properties of trailer components can be detected and reported to the evaluation unit. The evaluation unit can evaluate the report signals and can optionally output a preferably cause-specific alarm via the alarm means.The sensor device can have, for example, a sensor on the parking brake, which detects its position, in particular the opening and / or closing position. Another sensor can be arranged on a support wheel and can detect its position, in particular the retracted and / or extended position, for example. Other sensors can be, inter alia, proximity sensors which, for example, monitor the environment for collision hazards in a maneuvering operation of the vehicle trailer or which ensure that the actuation of a maneuvering drive takes place with a remote control outside the towing vehicle.The sensory detection device can thus have a multiple use for the vehicle trailer and its possible further trailer components. The sensory detection device, in particular its evaluation unit and the alarm means, can have a central function for the vehicle trailer.The evaluation unit, the alarm means and, if appropriate, the energy supply of the sensory detection device can be arranged on the preferably pivotable operating element. They can be arranged in particular on the friction brake lever of a friction brake. The lighting device can likewise be arranged on the preferably pivotable operating element, in particular on the friction brake lever.The lever bridge is particularly suitable for this arrangement(s) for reasons of space, function and accessibility. The arrangement on the lever bridge also facilitates retrofitting or retrofitting existing trailer couplings, in particular those with a friction brake. The lever bridge according to the invention with the components of the sensory detection device and / or the lighting device can be replaced by an existing lever bridge.The evaluation unit, the alarm means and optionally the energy supply and the lighting device can be connected to form a structural unit and arranged jointly on said operating element, in particular on the friction brake lever. Said structural unit or also said components of the lighting device and / or of the sensory detection device can be arranged at a distance above the coupling housing and at a rearward offset with respect to the coupling receptacle. They can be located in a receiving space on the upper side of the friction brake lever, in particular the lever bridge.This arrangement has advantages for the trouble-free accommodation of said components and in particular of the structural unit. Furthermore, this arrangement is advantageous for the visibility of an alarm element.The position is favorable for the lighting device in order to illuminate the front region of the trailer coupling and also the front environment. In poor visibility conditions, this facilitates maneuvering of the vehicle trailer when approaching and coupling to a towing vehicle. In this case, it is favorable if the lighting device comprises one or more lighting means. At least one lighting means can advantageously be directed towards the hitch receptacle and can illuminate said front region of the trailer hitch and its environment. One or more other lighting means can be arranged at another location, in particular on the opposite side, and can light up, for example, from the trailer coupling to the rear toward the vehicle trailer and its structure.This can be advantageous in order to carry out activities in the case of poor visibility at the front of a trailer superstructure or in the rear region of a drawbar of the vehicle trailer, for example loading and unloading bicycles, gas tanks or the like. The lighting device can be switched on and off as required via a switch. The lighting device can also be activated during the switching on over a predetermined period of time and can then switch off again by itself.A vehicle trailer equipped with the trailer coupling may benefit from the aforementioned advantages and may provide the user with a better and more comfortable amount of use.The dependent claims specify further advantageous embodiments of the invention.The invention is illustrated by way of example and schematically in the drawings. In detail, the following are shown: FIG. 1 : a broken-away side view of a towing vehicle and of a vehicle trailer with a trailer coupling, FIG. 2 : a plan view of the vehicle trailer according to arrow II of FIG. 1, FIG. 3 : a perspective view of the trailer coupling, FIGS. 4 and 5 are a top view and a rear perspective view of the tow hitch of FIG. 3 , FIGS. 6 to 8 are sectional views of the trailer coupling viewed from above, from the front and from the side, FIG. 9 is an exploded perspective view of the trailer coupling and a front cap, FIG. 10 is a fragmentary and enlarged side sectional view of the tow hitch and a mechanical hitch indicator in various positions, FIG. 11 is an exploded view of the mechanical coupling display and its components together with the sensor unit, FIGS. 12 and 13 show variants of a display element and a sensor unit, FIG. 14 is an exploded view of a sensor-type detection device on a friction brake lever in its closed position; and FIG. 15 : shows the trailer coupling and the friction brake lever in an open position.The invention relates to a trailer coupling (1) for a road-engaging vehicle trailer (2) and to the vehicle trailer (2) equipped with the trailer coupling (1).The vehicle trailer ( 2) is designed for driving on roads and in the combination with a towing vehicle ( 10), in particular a motor vehicle. The forward direction of travel is marked by an arrow in FIGS. 1 and 2.The vehicle trailer ( 2) comprises a chassis ( 5) which is formed from two or more longitudinal beams and a drawbar ( 5') at the front in the forward direction of travel and optionally one or more cross beams. The drawbar ( 5') is preferably designed as a rigid drawbar and in particular as a V drawbar. It carries the trailer coupling (1) at its front end. A support wheel ( 61) can be arranged on the drawbar ( 5'). A structure indicated in FIG. 1 can be arranged on the chassis (5).On the chassis (5) of the vehicle trailer (2), one or more axles with vehicle wheels (3) and wheel brakes (4) on both sides are arranged. The vehicle trailer ( 2) can comprise a service brake and a parking brake ( 60), in particular a hand brake. The service brake is designed, for example, as a run-on brake ( 6). This comprises a preferably translationally and linearly movable ramp element (7), at the front end of which the trailer coupling (1) is fastened with its coupling housing (13). The run-on brake (6) actuates the wheel brakes (4) when the vehicle trailer (2) runs onto the towing vehicle (10).The ramp element (7) is designed, for example, as a displaceably mounted and cylindrical rod. It acts in a suitable manner on the wheel brakes ( 4), for example mechanically via a brake linkage and a balance beam and brake trains ( 8) arranged there. The retraction and extension movements of the ramp-up element (7) which are produced during the running-on of the vehicle trailer (2) and during the subsequent acceleration of the towing vehicle (10) are transmitted to the brake linkage, for example, via a deflection lever which is not illustrated. The service brake can alternatively be designed in another manner, for example as a hydraulic, pneumatic or electric brake. The run-on element ( 7) can also be arranged in a fixed position and can detect a run-on of the vehicle trailer ( 2) onto the towing vehicle by sensor means, for example by means of strain gauges.In the embodiment shown, the vehicle trailer ( 2) also comprises a stabilization device ( 9) which actuates the wheel brakes ( 4) and dampens the roll movements when roll movements of the vehicle trailer ( 2) occur. The rolling movements can comprise skidding movements about a vertical axis and rolling movements about the longitudinal axis of the vehicle trailer ( 2). The stabilization device (9) can have a sensor system (9'), e.g. a yaw rate sensor and lateral acceleration sensors, an ESP unit or the like, with the aid of which the roll movements mentioned can be detected and evaluated, wherein, if a predetermined limit value of the roll movement is exceeded, the wheel brakes (4) can be controlled or optionally also actuated in a controlled manner by the stabilization device (9) and its, e.g. motor actuator. The vehicle trailer ( 2) can also comprise a maneuvering drive ( 62), indicated in FIG. 1, having drive units which can be delivered and controlled for the vehicle wheels ( 3).The trailer coupling ( 1) is illustrated in more detail in FIGS. 3-15. In the embodiments shown, it also comprises a friction brake (18). In a modified embodiment, the friction brake (18) can also be omitted.The trailer coupling (1) is adapted to the towing coupling (11) of the towing vehicle (10) and its coupling element (12). The trailer coupling is designed, for example, as a ball-head coupling, wherein the coupling element is designed as a coupling ball. Alternatively, other configurations are possible.The trailer coupling (1) comprises a coupling housing (13) with a hollow coupling receptacle (17) for the coupling element (12) on the towing vehicle side. The trailer coupling (1) also has a coupling mechanism (14) which is arranged in the coupling housing (13) and is designed for opening and closing the trailer coupling (1).The trailer coupling (1) further comprises a preferably pivotable operating element (22). Depending on the design of the trailer coupling (1), the operating element (22) can comprise a coupling lever (23) for actuating the coupling mechanism (14) and / or a friction brake lever (24) of a friction brake (18).The clutch housing (13) can be fixedly connected to the front end of the run-on element (7) according to FIG. 3. The clutch housing (13) has a shell shape, as can also be seen in FIG. 5. As the longitudinal sections of FIGS. 8, 10 and 11 show, the clutch mechanism ( 14) is arranged in the clutch housing ( 13) and is connected to the clutch lever ( 23) pivotably mounted on the clutch housing ( 13). The clutch mechanism (14) comprises, for example, a pivotable actuating lever (15) which is actuated by the clutch lever (23) and acts on a clutch shell (16) at its front end. The coupling shell (16) is rotatably mounted in the coupling housing (13) and forms a part of the shell-shaped or dome-shaped coupling receptacle (17) in which the coupling element (12) on the towing vehicle side, in particular the coupling ball, can be received in a form-fitting manner. By rotating the coupling shell (16), the coupling receptacle (17) and the trailer coupling (1) can be opened and closed.The clutch shell (16) is arranged, for example, at the rear region of the clutch receptacle (17). The front and lateral region of the clutch receptacle (17) can be formed by the wall of the clutch housing (13) and / or optionally by a plurality of friction elements of the friction brake (18). These friction elements can comprise, for example, a front friction shell (20), shown in the sectional representations, with its own adjustability and lateral friction plungers (19) on both sides.On the front side of the clutch housing ( 13), which is located at the front in the front-direction of travel, a front cap ( 21) made of a compressible and shock-absorbing material can be arranged. The front cap (21) may be removable. FIG. 9 shows the arrangement in an exploded view.The friction brake (18) present in the exemplary embodiments comprises, for example according to the horizontal and vertical sectional representations of FIGS. 6 and 7, the friction plungers (19) on both sides, which can be pressed laterally in each case onto the clutch element (12) located in the clutch receptacle (17), in particular the clutch ball, with their front-side friction lining. The actuation and pressing of the friction plungers ( 19) takes place via the friction brake lever ( 24).The friction brake lever (24) comprises, for example, two parallel lever arms (25, 26) which are connected at their front end to a pivotable lever mounting (29). A plunger actuator (31), for example a slide guide shown in FIG. 6, is connected in each case on the one hand to a lever arm (25, 26) and on the other hand via a spring arrangement (30) to a friction plunger (19). A rotational movement of the lever arms (25, 26) is converted via the plunger actuation (31) and the spring arrangement (30) tensioned in the process into a translatory feed movement of the relevant friction plunger (19).The parallel lever arms (25,26) may be connected at their rearward ends to a lever bridge (27) which receives the lever arm ends and bridges the distance between them and is provided at the rearward end with a handle (28). The friction brake lever (24) can be pivoted via the handle (28) and the friction brake (18) can be opened and closed thereby. FIGS. 3-11 show the closing and actuating position in which the friction brake lever (24) is pivoted in the direction of the clutch housing (13). FIG. 15 shows the open position of the friction brake (18), in which the friction brake lever (24) is pivoted upward about the axis of rotation of the lever mounting (29) shown in the drawings.In the open position, the friction followers (19) are released from the coupling element (12), so that the trailer coupling (1) can be opened by actuating the exposed coupling lever (23) and the vehicle trailer (2) can be uncoupled or coupled to the towing coupling (11). In the closed position, the friction brake lever (24) covers the clutch lever (23) pivoted into the illustrated rest position.As the longitudinal sections of FIGS. 8, 10 and 11 show, a wear indicator (32) can also be arranged on the clutch housing (13), which detects and indicates any wear of the clutch shell (16). The wear indicator detects the wear-dependent rotational position of the adjusting lever (15) and is pushed out of a frontal opening of the clutch lever (23) to a corresponding extent. Depending on the position of application, different color markings can be visible, which signal the wear state.The trailer coupling (1) has a mechanical coupling indicator (33), which detects and indicates correct coupling of the trailer coupling (1) to the coupling element (12) on the towing vehicle side. In this case, it is established whether the coupling element (12) is received correctly and completely in the coupling receptacle (17) and can be locked or locked by means of the coupling mechanism (14). This is referred to as the correct coupling position.The mechanical coupling indicator (33) comprises a movable and pin-like indicator element (34) which comprises a e.g. straight and cylindrical shaft (34') as well as an outer indicator head (35). The indicator head (35) is arranged at the free end of the indicator element (34), in particular its shaft (34'), which is spaced from the coupling receptacle (17). The display head (35) can have a laterally widened shape with respect to the shaft (34'). It may also have a colour marking or another signal means.The indicator element (34) is arranged with its shaft (34') in a receiving opening (38) on the coupling housing (13). The receiving opening (38) opens on the one hand at the coupling receptacle (17) and on the other hand has an outer end region (39), spaced therefrom, on the outer side of the coupling housing (13). The receiving opening (38) is located at the upper and / or front region of the clutch receptacle (17) and of the clutch housing (13). The receiving opening (38) preferably has a straight and, in the case of a ball-head coupling, radial extension relative to the center of the ball-shell-shaped coupling receptacle (17).The indicator element (34) is movable with its shaft (34') in the receiving opening (38) and is arranged under the action of a restoring spring (40). The indicator element (34), which normally protrudes into the cavity of the coupling receptacle (17), is contacted by the immersed coupling element (12) and displaced out of the starting position (36) shown in FIG. 10. When the correct coupling position is assumed, the display element (34) is displaced by the coupling element (12) into an optically recognizable display position (37) on the coupling housing (13). FIG. 10 shows this display position (37) in a dashed representation.In the display position (37), the display element (34), in particular its display head (35), projects outwards beyond the coupling housing (13) and also the optionally present front cap (21). This projecting display position (37) signals the correct coupling position. If the coupling element (12) is not completely immersed in the coupling receptacle (17), the display element (34) is only partially displaced and moved out of the receiving opening (38). The, for example, dome-shaped display head (35) is then still partially located in the region of the through-opening in the front cap (21) and is still positioned close to the coupling housing (13). This intermediate position differs in a recognizable manner from the correct display position (37), wherein a color marking on the display element (34) is possibly also visible only in the display position (37).The trailer coupling (1) additionally has a sensor detection device (41) with a sensor unit (42) which is assigned to the display element (34) and detects and signals the displacement thereof and / or the departure thereof from the starting position (36) and / or the acceptance thereof of the display position (37). The sensor unit (42) likewise detects a correct coupling of the trailer coupling (1) to the coupling element (12) on the towing vehicle side and signals this.As FIGS. 8-14 show, the sensor unit (42) is arranged at the outer end region (39) of the receiving opening (38). As is shown in particular by the exploded view of FIG. 11, the sensor unit (42) or a part thereof can be arranged on a sleeve-shaped insert part (42a), which can be mounted in the receiving opening (38), for example by clipping in or in another way, and which accommodates the display element (34) in a longitudinally movable manner. This configuration allows a display element ( 34) according to the invention and a sensor unit ( 42) to be retrofitted or re-fitted on a trailer coupling ( 1).The sensor unit (42) may be provided individually or several times. It can also be designed in different ways. FIGS. 10-13 illustrate various possible embodiments.In FIGS. 10 and 11 and FIG. 13, the sensor unit (42) comprises a plurality of interacting sensor elements (42', 42") which are arranged alternately on the receiving opening (38) and on the display element (34), in particular on the display head (35). In the variant of FIGS. 10 and 11, for example, the sensor element ( 42') arranged on the receiving opening ( 38), in particular on the insert part ( 42 a), is designed as a Hall sensor. The other sensor element ( 42") is arranged on the inside of the, for example, hood-shaped display head ( 35) and is designed as, for example, an annular magnet. In the starting position ( 36) shown in FIG. 10, the magnet ( 42"), for example, is arranged very close to and possibly in contact with the Hall sensor ( 42'). The Hall sensor ( 42') detects displacement of the indicator element ( 34) and removal of the magnet ( 42").In the embodiment of FIG. 13, for example, the sensor element ( 42') arranged on the receiving opening ( 38) or on the clutch housing ( 13) is designed as an inductive proximity sensor, which interacts with a sensor element ( 42") in the form of a metal plate arranged on the display element ( 34). The displacement movement and the assumption of the starting position ( 36) and the display position ( 37) are detected and signaled by detecting the different distances between the sensor elements ( 42', 42").In a modification of the embodiment shown in FIG. 13, the sensor unit ( 42) can comprise a contact switch which is designed, for example, as an end position switch and which can be arranged on the receiving opening ( 38) or on the clutch housing ( 13). Such an end position switch can detect the display position (37), for example, wherein a projection or the like of the display element (34) then strikes against the end position switch.FIG. 12 shows another form of sensor unit (42) in the form of a contact switch. This is designed, for example, as a slide switch with permanent contact with the display element (34) by means of a wedge guide. When the display element (34) moves in the receiving opening (38), the slide switch (42) is laterally displaced via the wedge guide. Depending on the displacement path, the sliding movement of the contact switch is smaller or larger. It can be recorded by measurement technology in a suitable manner, for example by a potentiometer or the like. By appropriate calibration, the displacement path and the starting and display position (36, 37) can be detected and signaled.The sensor detection device ( 41) can furthermore comprise an evaluation unit ( 43), e.g. with a printed circuit board ( 44), and an alarm means ( 47), which is connected to the evaluation unit ( 43). The evaluation unit ( 43) can be coupled to the sensor unit ( 42) by a signal means ( 45). The signal means ( 45) can be designed as a cable, for example, according to the longitudinal sections of FIGS. 8, 10 and 14.The sensory detection device ( 41) can furthermore have its own power supply ( 46), for example an electric battery. This can likewise be coupled to the sensor unit (42) via the signal means (45). The said couplings can in particular be provided with the opening-side sensor element ( 42').The evaluation unit ( 43) can record and evaluate the signals of the sensor unit ( 42). It can determine where the display element (34) is located and whether or not the correct coupling position is assumed when the display element (34) is displaced. The evaluation unit ( 43) can signal the evaluation result to the outside via the alarm means ( 47) such that it can be recognized by an operator. The alarm means ( 47) can output a cause-specific alarm optically and / or acoustically. The operator can recognize the cause for the alarm triggering from this and obtain information for remedying the cause or the fault.As FIGS. 4, 8 and 14 show, the alarm means can comprise one or more light elements (48), which are formed by LEDs, for example. The alarm means (47) can signal different evaluation results by light modulation, for example by continuous light, flashing light or the like.As FIG. 14 illustrates, the sensory detection device ( 41) can also comprise a preferably wirelessly communicating communication means ( 56), which is arranged, for example, on the evaluation unit ( 43), in particular on its printed circuit board ( 44). The communication means ( 56) is e.g. a pure transmission unit. It can alternatively be a pure receiving unit or a combination of transmitting and receiving units. The preferably wireless communication can be effected e.g. by radio, Bluetooth, WLAN, infrared light or in another manner. The communication means (56) can also be part of the alarm means (47).The communication can be performed with an external other communication means which is arranged, for example, on a remote control (58) illustrated in FIGS. 1 and 2. The remote control ( 58) can be e.g. mobile and portable or can be implemented on the vehicle trailer ( 2) and / or on the towing vehicle ( 10). It can have, for example, at least one display and, if appropriate, one or more input elements, for example buttons, touchscreen or the like. On the display, for example, the evaluation results of the evaluation unit ( 43) and / or an alarm in the event of a faulty coupling position can be signaled in a suitable manner, for example optically and / or acoustically.The evaluation unit ( 43), the alarm means ( 47) and, if appropriate, the energy supply ( 46) can be arranged on the preferably pivotable operating element ( 22). In the exemplary embodiments shown, this is the friction brake lever ( 24). If, in another variant of the trailer coupling (1), the friction brake (18) and in particular a friction brake lever (24) are absent, the arrangement can also be made on the coupling lever (23).The evaluation unit ( 43), the alarm means ( 47) and optionally the energy supply ( 46) are preferably arranged at a distance above the clutch housing ( 13) and at a rearward offset with respect to the clutch receptacle ( 17) on the preferably pivotable operating element ( 22).In the embodiments shown, the trailer coupling (1) also comprises a lighting device (49), which is preferably likewise arranged on the preferably pivotable operating element (22), in particular on the friction brake lever (24) or on the coupling lever (23). The illumination device ( 49) is likewise preferably arranged at a distance above the coupling housing ( 13) and with a rearward offset with respect to the coupling receptacle ( 17).In contrast to the exemplary embodiments shown, the trailer coupling ( 1) can comprise the illumination device ( 49), wherein it can otherwise be configured in a conventional manner and in particular without the sensory detection device ( 41). In a trailer coupling (1) with a lighting device (49), a friction brake (18) may also be absent.The lighting device ( 49) comprises one or more lighting means ( 50, 51, 52). At least one lighting means (50) is directed with its emission direction towards the coupling receptacle (17) and illuminates the region of the trailer coupling (1) there. One or more other lighting means (51, 52) can emit light in the opposite direction. In addition, a lateral arrangement of lighting means(s) is possible. The lighting means (50, 51, 52) can be switched differently, in particular depending on the closing or opening position of the friction brake lever (24). The rear lighting means (51, 52) can be switched off, for example, in the open position of the friction brake lever (24) according to FIG. 15, in order not to blind an operator. The lighting device ( 49) can also comprise a switch ( 53).The evaluation unit ( 43), the alarm means ( 47) and, if appropriate, the energy supply ( 46) and the illumination device ( 49) are connected to form a structural unit ( 57) in the exemplary embodiments shown. The structural unit (57) can comprise a housing of its own and the components mentioned. The arrangement is shown, for example, in the exploded view of FIG. 14.The structural unit (57) is arranged on the preferably pivotable operating element (22), in particular on the friction brake lever (24). It is located, for example, in a receiving space (54) on the upper side of the friction brake lever (24), in particular of the lever bridge (27). The illumination device (49) and the aforementioned components of the sensory detection device (41) can also be arranged individually and optionally separately from one another in said receiving space (54). In an alternative arrangement on a clutch lever (23), the design and arrangement are correspondingly changed.As FIG. 8 shows, the trailer coupling ( 1) can have a sensor system ( 55) on the coupling housing ( 13). The sensor system ( 55) can record one or more physical parameters of the vehicle trailer ( 2) in the tension mode. These can be, for example, force, travel and / or acceleration. These physical parameters can occur during braking of the towing vehicle ( 10) and during running on of the vehicle trailer ( 2) and during subsequent acceleration of the towing vehicle ( 10). They can be directed differently, for example in the longitudinal direction of the vehicle trailer ( 2) and optionally in a transverse direction. The path can be, for example, the axial run-up path or pull-out path on the run-up brake (6), in particular on its run-up element (7). The acceleration can be recorded, for example, in the direction of travel.The sensor system ( 55) can be formed in one piece or in multiple pieces depending on the type and number of physical parameters to be recorded by measurement technology. A force occurring during the run-on or acceleration can be recorded by one or more strain gauges on the wall of the clutch housing ( 13) or by measurement in another manner, for example. A ramp-up path or ramp-up path can be detected, for example, by a path sensor which records the movement of the trailer coupling ( 1) relative to a stationary part of the drawbar ( 5) by measurement technology.The sensor system ( 55) can be connected in a suitable manner to the evaluation unit ( 43) and, if appropriate, to the energy supply ( 46) and, in particular, to the communication means ( 56). In this case, for example, a communication connection can be established between the communication means ( 56) and a communication means, not shown, of the sensor system ( 55).The evaluation unit ( 43) can evaluate the measured and communicated physical parameters in different ways. It can determine the current mass of the vehicle trailer ( 2), for example. The result of the determination can be communicated to the evaluation device ( 43), for example, to the stabilization device ( 9) in a suitable manner via a communication connection. The stabilization device ( 9) can set the strength of the braking intervention of the wheel brakes ( 4) as a function of the actual trailer mass and can optionally also align the control behavior according to this.If, in a variant which is not shown, the vehicle trailer ( 2) comprises an anti-lock brake system (ABS) for the actuation of the wheel brakes ( 4), the current trailer mass determined by the evaluation unit ( 43) can likewise be communicated to said vehicle trailer and used there for the control and, if appropriate, regulation of the anti-lock brake.In another embodiment, which is likewise not illustrated, the vehicle trailer ( 2) can have a so-called electric axle which comprises an electric drive and preferably regenerative braking unit. The electric driving and braking can be made dependent on said physical parameters detected by the sensor system (55).Alternatively or in addition to an evaluation result, the evaluation unit ( 43) can also transmit the measurement data of the sensor system ( 55) to said receivers of the stabilization device ( 9), of the ABS system or of the electrical axis. Said communication link may be wired and / or wireless. The communication connection can be established in particular via the communication means ( 56) on the evaluation unit ( 43). The communication link may be unidirectional or bidirectional.As FIG. 2 schematically illustrates, the vehicle trailer ( 2) can have a sensor device ( 59). This can comprise one or more sensors, not shown. A sensor can be arranged on the parking brake (60), for example, and can detect its position, in particular the open and / or closed position. Another sensor can be arranged on the support element ( 61), for example, and can detect its position, in particular the retracted and / or extended position. One or more further sensors can be arranged on the chassis ( 5) and / or on the superstructure. They can detect, for example, the approach of the e.g. ranked vehicle trailer ( 2) to an obstacle. FIG. 1 shows a proximity sensor of the sensor device ( 59) arranged on the drawbar ( 5'), which proximity sensor is triggered by a remote control of a maneuvering drive and ensures that the operator is located outside the towing vehicle ( 10) during the operation of the maneuvering drive.The sensor device ( 59) can communicate with the evaluation unit ( 43) via the communication center ( 56) and transmit the sensor signals for evaluation and, if applicable, for triggering a preferably cause-specific alarm.Modifications of the described exemplary embodiments shown are possible in various ways and within the scope of the claims. In particular, the claimed features of the exemplary embodiments shown and described and of the variants mentioned can be combined with one another and optionally interchanged.LIST OF REFERENCE CHARACTERS1 Trailer coupling 2 Vehicle trailer 3 Vehicle wheel 4 Wheel brake 5 Chassis 5' Drawbar 6 Run-on brake 7 Run-on element 8 Brake cable 9 Stabilizing device 9' Sensor system 10 Towing vehicle 11 Towing coupling 12 Coupling element, coupling ball 13 Coupling housing 14 Coupling mechanism 15 Adjusting lever 16 Coupling shell 17 Coupling receptacle, ball receptacle 18 Friction brake 19 Friction plunger 20 Friction shell 21 Front cap 22 Operating element 23 Coupling lever 24 Friction brake lever 25 Lever arm 26 Lever arm 27 Lever bridge 28 Handle 29 Lever mounting 30 Spring arrangement 31 Plunger actuation, link guide 32 Wear indicator 33 Coupling indicator mechanically 34 Indicator element, Indicator pin 34' Shaft 35 Indicator head 36 Initial position 37 Indicator position 38 Receiving opening 39 Outer end region 40 Spring 41 Detection device 42 Sensor unit 42' Sensor element 42" Sensor element 42 a Einsatz part 43 Evaluation device 44 Circuit board 45 Signal means, line 46 Energy supply 47 Alarm means 48 Light element 49 Lighting device 50 Lighting means 51 Lighting means 52 Lighting means 53 Switch 54 Receiving space 55 Sensor system 56 Communication means 57 Structural unit 58 Remote control 59 Sensor device 60 Parking brake 61 Support wheel 62 Maneuvering driveReferences included in the specificationThis list of documents cited by the applicant has been produced in an automated manner and is only included for the better information of the reader. The list is not part of the German patent application or utility model application. The DPMA does not take any adhesion for any faults or omissions.Patent Literature citedDE 20 2009 005 185 U1

[0003] DE 94 12 514 U1

[0003] DE 10 2020 119 506 A1

[0004] DE 10 2022 123 784 A1

[0005] DE 11 2022 005 586 T5

[0006]

Claims

Trailer coupling for a road-based vehicle trailer (2), wherein the trailer coupling (1) comprises a coupling housing (13) with a coupling receptacle (17) for a coupling element (12) on the towing vehicle side, a coupling mechanism (14) designed for opening and closing the trailer coupling (1) and a preferably pivotable operating element (22), characterized in that the trailer coupling (1) - comprises a mechanical coupling indicator (33) which detects and indicates correct coupling of the trailer coupling (1) to a coupling element (12) on the towing vehicle side, wherein the mechanical coupling indicator (33) has a movable, preferably pin-like, display element (34) with an outer display head (35), which is arranged in a receiving opening (38) on the coupling housing (13) and, when the towing vehicle-side coupling element (12) is correctly coupled, can be displaced from an initial position (36) into an optically recognizable display position (37) on the coupling housing (13), wherein - the trailer coupling (1) additionally comprises a sensory detection device (41) with a sensor unit (42) which detects a correct coupling of the trailer coupling (1) on the towing vehicle-side coupling element (12), wherein the sensor unit (42) is assigned to the display element (34) and detects and signals its displacement and / or its departure from the initial position (36) and / or its acceptance of the display position (37).Trailer coupling according to the preamble of claim 1 or according to claim 1, characterised in that the trailer coupling (1) has a lighting device (49) which is arranged on the operating element (22).Trailer coupling according to Claim 1 or 2, characterized in that the trailer coupling (1) is designed as a ball-head coupling and is provided and designed for a towing vehicle-side coupling element (12) designed as a coupling ball.Trailer coupling according to claim 1, 2 or 3, characterised in that the trailer coupling (1) comprises an actuatable friction brake (18) which is provided and designed for cooperation with the coupling element (12) on the towing vehicle side.Trailer coupling according to one of the preceding claims, characterized in that the preferably pivotable operating element (22) is designed as a coupling lever (23) for actuating the coupling mechanism (14) or as a friction brake lever (24) of a friction brake (18).Trailer coupling according to one of the preceding claims, characterized in that the friction brake (18) has spring-loaded friction plungers (19) which can be pressed by the preferably pivotable friction brake lever (24) onto the coupling element (12) on the towing vehicle side by means of a lever mounting (29) and a plunger actuation (31), in particular a link guide.Trailer coupling according to one of the preceding claims, characterized in that a friction brake lever (24) of a friction brake (18) comprises pivotable lever arms (25, 26) connected to a lever mounting (29) and a lever bridge (27) which is arranged between the lever arms (25, 26) and can be exchanged if appropriate.Trailer coupling according to one of the preceding claims, characterized in that the sensor unit (42) is arranged on the outer end region (39) of the receiving opening (38).Trailer coupling according to one of the preceding claims, characterized in that the sensor unit (42) comprises a plurality of interacting sensor elements (42', 42"), which are arranged alternately on the display element (34), in particular on the display head (35), and on the receiving opening (38).Trailer coupling according to one of the preceding claims, characterized in that the sensor elements (42', 42") comprise a Hall sensor and a magnet.Trailer coupling according to one of the preceding claims, characterized in that the sensor unit (42) comprises a contactless inductive proximity sensor.Trailer coupling according to one of the preceding claims, characterized in that the sensor unit (42) comprises a contact switch, wherein the contact switch is designed as an end position switch with temporary contact with the display element (34) or as a slide switch with permanent contact with the display element (34) by means of a wedge guide.Trailer coupling according to one of the preceding claims, characterized in that the sensory detection device (41) has a preferably sleeve-like insert part (42a) which is designed for arrangement in the receiving opening (38) and for guiding the movable display element (34) and for receiving the sensor unit (42), in particular a sensor element (42').Trailer coupling according to one of the preceding claims, characterized in that the sensory detection device (41) has an evaluation unit (43) and an alarm means (47) connected thereto and optionally an energy supply (46), which are coupled to the sensor unit (42) by a signal means (45), in particular a cable.Trailer coupling according to one of the preceding claims, characterized in that the sensory detection device (41) comprises a wirelessly communicating communication means (56), which is preferably arranged on the evaluation unit (43).Trailer coupling according to one of the preceding claims, characterized in that the alarm means (47) comprises one or more light elements (48) and / or optionally the communication means (56).Trailer coupling according to one of the preceding claims, characterized in that the trailer coupling (1) has a sensor system (55) on the coupling housing (13), which is provided and designed to absorb one or more physical parameters of the vehicle trailer (2) in the clamping mode, in particular force, travel and / or acceleration.Trailer coupling according to one of the preceding claims, characterized in that the sensor system (55) is connected to the evaluation unit (43), the possible energy supply (46) and the communication means (56).Trailer coupling according to one of the preceding claims, characterized in that the evaluation unit (43) is connected to a sensor device (59) of the vehicle trailer (2).Trailer coupling according to one of the preceding claims, characterized in that the evaluation unit (43), the alarm means (47) and optionally the energy supply (46) are arranged on the preferably pivotable operating element (22), in particular on a friction brake lever (24) of a friction brake (18).Trailer coupling according to one of the preceding claims, characterized in that the evaluation unit (43), the alarm means (47) and, if appropriate, the energy supply (46) and the lighting device (49) are connected to form a structural unit (57) and are arranged jointly on the preferably pivotable operating element (22), in particular on a friction brake lever (24) of a friction brake (18).Trailer coupling according to one of the preceding claims, characterized in that the evaluation unit (43), the alarm means (47) and optionally the energy supply (46) and optionally the lighting device (49), in particular the structural unit (57), is / are arranged on the friction brake lever (24) at a distance above the coupling housing (13) and with a rearward offset with respect to the coupling receptacle (17) in a receiving space (54) on the upper side of the friction brake lever (24).Trailer coupling according to one of the preceding claims, characterized in that the lighting device (49) comprises one or more lighting means (50, 51, 52), wherein at least one lighting means (50) is directed towards the coupling receptacle (17).Trailer coupling according to one of the preceding claims, characterized in that the lighting device (49) has a switch (53).Road-engaging vehicle trailer (2) having a trailer coupling (1) which comprises a coupling housing (13) having a coupling receptacle (17) for a coupling element (12) on the towing vehicle side, a coupling mechanism (14) designed for opening and closing the trailer coupling (1) and a preferably pivotable operating element (22), characterized in that the trailer coupling (1) is designed according to at least one of Claims 1 to 24.Vehicle trailer according to claim 25, characterised in that the vehicle trailer (2) has a chassis (5) with a preferably rigid drawbar (5'), at the front end of which the trailer coupling (1) is arranged.Vehicle trailer according to Claim 25 or 26, characterized in that the vehicle trailer (2) has vehicle wheels (3) with wheel brakes (4) and a service brake, in particular a run-on brake (6), wherein the trailer coupling (1) is preferably fixedly connected to a run-on element (7) of the service brake, in particular run-on brake (6).Vehicle trailer according to Claim 25, 26 or 27, characterized in that the vehicle trailer (2) has a parking brake (60) and a supporting wheel (61).Vehicle trailer according to one of Claims 25 to 28, characterized in that the vehicle trailer (2) has a sensor device (59) which communicates with the sensory detection device (41), in particular with the evaluation device (43) thereof.Vehicle trailer according to one of Claims 25 to 29, characterized in that the sensor device (59) comprises one or more sensors on the parking brake (60) and / or on the supporting wheel (61) and / or on the chassis (5).Vehicle trailer according to one of Claims 25 to 30, characterized in that the vehicle trailer (2) has a stabilization device (9) which communicates with the sensory detection device (41), in particular with the evaluation device (43) thereof.Vehicle trailer according to one of Claims 25 to 31, characterized in that the vehicle trailer (2) has an electrical axle with an electrical drive and brake device for vehicle wheels (3) of the vehicle trailer (2), which device communicates with the sensory detection device (41), in particular with the evaluation device (43) thereof.

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