The invention relates to a trailer coupling for a motor vehicle, in particular a passenger car, comprising a retainer which is arranged on or can be fastened to the motor vehicle, and a retainer part, which can be detachably fastened to the retainer and which has a retainer insertion projection for inserting into a retainer insertion receptacle of the retainer, wherein the retainer part has an integrated locking device having at least one locking body and has an actuation body, which is supported in the retainer part so as to be movable in order to actuate the at least one locking body into a locking position, wherein the at least one locking body interlocklingly engages in a locking receptacle on the retainer in the locking position and is moved out of the locking receptacle in a detaching position, wherein the retainer part is provided for forming a coupling arm, which has a coupling part having a coupling element, in particular a coupling ball, for coupling a load carrier or a trailer, or for directly coupling a load carrier.

A trailer coupling of this type is explained in DE 10 2011 009 306 A1. The known trailer coupling can be adapted to various requirements so that different coupling elements can be mounted, for example. However, the flexibility of the known trailer coupling is still not ideal.

The objective of the present invention is therefore to provide an improved trailer coupling.

In order to achieve this objective, provision is made in the case of the aforementioned type of trailer couplings that the retainer part has a receiving sleeve with a tubular coupling insertion receptacle for inserting a coupling insertion projection of the coupling part or of the load carrier.

The following is also part of the invention: trailer coupling for a motor vehicle, in particular a passenger motor vehicle, having a retainer arranged on or fastened to the motor vehicle and a coupling arm detachably fastened to the retainer, wherein the coupling arm comprises a retainer part with an insertion projection for insertion into a retainer insertion receptacle of the retainer and a coupling part with a coupling element, in particular a coupling ball, for coupling a load carrier or a trailer, or is provided for direct coupling of a load carrier, wherein the retainer part has an integrated locking device having at least one locking body and an actuation body, which is supported in the retainer part so as to be movable in order to actuate the at least one locking body into a locking position, wherein the locking body interlockingly engages in a locking receptacle on the retainer in the locking position and is moved out of the locking receptacle in a detaching position, the retainer insertion projection of the retainer part therefore being interlockingly locked in the retainer insertion receptacle of the retainer in the locking position of the at least one locking body and being removable from the retainer insertion receptacle of the retainer in the detaching position. Provision is made in the trailer coupling that the retainer part has a receiving sleeve with a tubular coupling insertion receptacle for inserting a coupling insertion projection of the coupling part or of the load carrier.

The coupling arm, i.e. the retainer part and the coupling part, can form parts of the trailer coupling.

It is also possible that the coupling part and the trailer coupling explained above form components of a system. Furthermore, it is possible that said system or a different system comprises firstly the trailer coupling according to claim1and secondly a load carrier and/or an adapter element of the load carrier which has the coupling insertion projection.

The advantage of this design is that the retainer part can be easily removed from the securely mounted retainer from the vehicle side, namely by releasing the locking device. The movable components of the locking device are arranged on the retainer part such that complicated and expensive installations on the motor vehicle are not necessary. No movable components of a locking device need to be fitted or installed on the motor vehicle for example. The retainer is generally hidden behind the vehicle bumper such that it is not directly accessible. If a locking device is then arranged directly on the motor vehicle in this region, Bowden cables, electrical cables or similar have to be fitted in a more circuitous manner, in the boot, for example, where corresponding handles or similar for actuating the locking device can be arranged. This is not the case with the invention.

Advantageously, all the movable components of the locking device are arranged on the retainer part, i.e. on a component of the coupling arm which can be removed from the retainer.

A manual actuation device, in particular on board the retainer part, is advantageous for actuating the at least one locking body. Preferably a turning knob, actuating lever or similar is provided for actuating the locking body. In any case, a manual actuation handle to actuate the locking device, in particular towards the release position, is advantageously a component of the coupling arm, in particular of the retainer part.

The receiving sleeve is suitable for fitting the most diverse coupling parts, but also a load carrier directly. A coupling part with a ball-shaped coupling element, namely a coupling ball, can be inserted into the receiving sleeve, for instance. A load carrier can be attached to the coupling element, however typically a trailer can be attached.

However, it is also possible that the coupling part itself has a receiving sleeve into which a load carrier can then be inserted for example.

Furthermore, it is possible that at least one coupling insertion projection is provided on a load carrier which can be inserted into the coupling insertion receptacle of the receiving sleeve. The retainer part according to the invention can therefore be inserted into the vehicle-side retainer as an intermediate piece to then enable fitting of a load carrier, the coupling insertion projection of which is inserted into the coupling insertion receptacle of the receiving sleeve. It is possible in this case that a trailer coupling according to the invention is provided approximately transversely centrally at the rear of the vehicle, for example, into which the load carrier can be inserted centrally so to speak. It is also possible, however, that two or more trailer couplings according to the invention are provided at the rear of the vehicle so that a load carrier with two supporting arms, on each of which a coupling insertion projection is provided, can be inserted into the respective receiving sleeve of the retainer part. The retainer parts are arranged on a carrier assembly at the same distance from the transverse centre of the motor vehicle.

It should be noted at this point that a carrier assembly, in particular a cross member, to which the vehicle-side retainer is fastened, can of course also form an integral part of the trailer coupling according to the invention.

In order that the coupling insertion projection cannot be pushed freely through the receiving sleeve, but stops there at a predefined insertion depth, an end stop is advantageously provided for a free front side of the coupling insertion projection on an internal cross section of the coupling insertion receptacle. The coupling insertion receptacle has a base against which the free front side of the coupling insertion projection strikes. The base can be a complete base forming the bottom area of the coupling insertion receptacle such that the coupling insertion receptacle is completely closed on the bottom side. It is also possible, however, that the base is only present in part, i.e. that a supporting element protrudes in the direction of the internal cross section of the coupling insertion receptacle and forms a partial base region there. Said supporting element then acts as an end stop.

A different version, also in combination with the above-mentioned version of the invention, advantageously makes provision that a stop is provided on the outer circumference of the coupling insertion projection for striking a free front side of the receiving sleeve. The stop on the outer circumference of the coupling insertion projection can be configured like a flange, for example. It is also possible, however, that the stop is formed by a protruding interlocking element, in particular a bolt or similar. The free front side of the receiving sleeve acting as a stop can be formed by the peripheral wall of the receiving sleeve for example. Consequently, the stop of the coupling insertion projection strikes the front side of the peripheral wall of the receiving sleeve.

Reinforcement or a dedicated stop on the front side of the receiving sleeve, in particular the peripheral wall thereof, is also advantageous as follows. It is possible that a flange projection, in particular a flange projection surrounding the free front side in a circular manner, is arranged on the free front side of the receiving sleeve to strike the coupling insertion projection.

The receiving sleeve can be formed by a tubular element. A sufficiently strong pipe or a sufficiently thick pipe wall are enough to guarantee the required stability.

An advantageous embodiment of the invention makes the provision that the receiving sleeve is reinforced by at least one reinforcing element. Reinforcing ribs or stiffening ribs are provided on a tubular body of the receiving sleeve, for example.

A preferred embodiment of the invention makes the provision that the receiving sleeve is reinforced by at least one reinforcing ring. The reinforcing ring acts as a stiffener. Advantageously, the reinforcing ring completely encloses the external perimeter of the receiving sleeve or a tubular piece or tubular body of the receiving sleeve. A reinforcing ring, which is configured only as a partial ring, i.e. does not enclose the entire external perimeter of the tubular piece or tubular body of the receiving sleeve, is also conceivable.

An advantageous embodiment makes the provision that the at least one reinforcing ring is arranged on a free front side of the receiving sleeve. Thus, reinforcement is provided exactly where the heaviest loading by the coupling part or the load carrier may occur. The reinforcing ring can display an additional function at this point, namely as a longitudinal stop for the coupling projection of the coupling part or load carrier.

Preferably, a locking arrangement is provided to lock the coupling insertion projection to the coupling insertion receptacle.

The locking arrangement advantageously comprises a locking element, for example a locking bar, bolt or similar, which can be inserted into a locking receptacle of the receiving sleeve or pushed through the locking receptacle.

It would be possible for example that the locking arrangement is configured similar to the one which is provided on the retainer insertion receptacle and the retainer insertion projection and is effective. However, the locking arrangement explained below is preferred.

The locking arrangement comprises, for example, a locking element, which can be inserted into a locking receptacle of the receiving sleeve or pushed through the locking receptacle. Advantageously, a plurality of locking receptacles, in particular push-through openings, are provided on the receiving sleeve. Pairs of push-through openings, which are located opposite each other or are flush with each other, are preferred so that the locking element can be pushed through said locking receptacles. The respective longitudinal ends of the locking element are angled or can be secured by a securing element, for example a circular cotter pin or similar.

A preferred embodiment of the invention makes the provision that locking receptacles are provided on the coupling insertion projection and the coupling insertion receptacle, which are flush with each other when the coupling insertion projection is inserted into the coupling insertion receptacle. The locking element can be pushed through the locking receptacle. A push-through opening is provided for the locking element on the coupling insertion projection, for example, which penetrates said push-through opening as well as further push-through openings provided as locking receptacles on the receiving sleeve. Thus, the coupling insertion projection can no longer be removed from the coupling insertion receptacle.

It is preferred if the coupling insertion receptacle and the coupling insertion projection have at least one anti-rotation contour for receiving the coupling insertion projection in the coupling insertion receptacle in a rotationally locked manner. An anti-rotation projection can be provided eccentric to the axis of insertion, for example. It is preferred if the coupling insertion receptacle and the coupling insertion projection have a polygonal cross section, for example a triangular or square cross section, in order to guarantee anti-rotation. A rectangular, in particular squarish cross section, is preferred. This means that corners or corner regions can be rounded so that the coupling insertion projection can be easily inserted into the coupling insertion receptacle.

The axis of insertion of the coupling insertion receptacle and the axis of insertion of the retainer insertion receptacle are advantageously angled, for instance at right-angles. However, angles deviating from a right angle, for example, angle of 80 or 110°, are also advantageous. In any case, the effective axes with which the coupling insertion receptacle and the coupling insertion projection on the one hand and the retainer insertion receptacle and retainer insertion projection on the other hand can be engaged or disengaged, are preferably angled relative to each other. An angle of 50°, for example, also ensures that an action of force, in the longitudinal direction of the vehicle, between the coupling insertion receptacle and the coupling insertion projection, does not act simultaneously as a force to pull the retainer insertion projection out of the retainer insertion receptacle.

A preferred embodiment of the invention, which is also shown in more detail in the drawings, makes the provision that an axis of insertion of the coupling insertion receptacle runs substantially in a horizontal direction. It is advantageous in the case of the retainer insertion receptacle and the retainer insertion projection if the axis of insertion runs substantially in a vertical direction. The vehicle-side retainer can thus be easily accommodated behind a bumper of the vehicle, for example, and the coupling part can be inserted into the vehicle-side retainer from below. Operation is easy and the arrangement is visually appealing.

It is possible that the receiving sleeve forms an integral part of the retainer part. It can be formed integrally by a retainer body of the retainer part, for example. The retainer body is a cast part or forged part, for example, on which the receiving sleeve is configured as a sleeve section.

An advantageous embodiment of the invention makes the provision that the receiving sleeve is detachably fastened to the retainer part, for example screwed, riveted or similar to the retainer part. The retainer part can thus be optionally provided with different receiving sleeves, for example, receiving sleeves with different cross sections. Fitting is simple and changeover is easy.

A preferred version of the invention makes the provision that the retainer part has a bifurcate attachment which holds the receiving sleeve. The receiving sleeve is pushed into the bifurcate attachment from below or from the front (depending on the position in which it is fitted on the vehicle). It can be secured or permanently fastened there using a screw and/or glued and/or welded or similar.

The bifurcate attachment can have prong-like arms or side arms, for example, which protrude downwards from the retainer insertion projection, i.e. towards the road (depending on the position in which it is fitted on the vehicle).

In other cases referred to above, if the receiving sleeve is pushed into the bifurcate attachment from the front, the bifurcate attachment has prong-like arms or legs protruding horizontally from the retainer insertion projection between which the receiving sleeve is accommodated.

It is advantageous if the attachment has side arms or legs against which walls, for example side walls, of the receiving sleeve rest.

In addition, it is advantageous if the attachment has a base against which the receiving sleeve rests.

The attachment for the receiving sleeve can also be ring-shaped so that the receiving sleeve can be inserted into the attachment.

It is advantageous in any case if a receiving space, which is defined by the attachment, accommodates a large part of the cross section of the receiving sleeve, while a smaller part of the cross section of the receiving sleeve protrudes from the attachment or is not accommodated in the receiving space.

The arms of the bifurcate attachment extend in a longitudinal direction away from a base of the attachment. A section of the receiving sleeve protruding from the arms is preferably shorter in relation to said longitudinal extension than a section of the receiving sleeve accommodated between the arms. In other words, it is advantageous if a larger part of the receiving sleeve in relation to a longitudinal extension of the arms of the attachment is arranged between the arms and a smaller part of the receiving sleeve protrudes from the arms.

It is advantageous in the case of a ring-shaped or bifurcate attachment, if provision is made that the receiving sleeve is supported on at least three sides of the attachment angled relative to each other.

The bifurcate attachment or also a ring-shaped attachment has prong-like arms or legs protruding from the retainer insertion projections of the retainer part.

The attachment, i.e. prong-like arms and legs, for example, preferably forms a single piece with the retainer insertion projection.

A preferred concept also makes provision that the receiving sleeve is arranged on the retainer insertion projection as below or a body of the retainer part, for example an arm body of the retainer part, which has the retainer insertion projection, has the following configuration:

Preferably provision is made that the receiving sleeve is arranged on the retainer insertion projection such that in the state of being mounted on the vehicle it protrudes from the retainer insertion projection towards a bumper of the motor vehicle and/or from the retainer insertion projection backwards contrary to a forward direction of travel of the motor vehicle.

Therefore, in the direction of travel of the motor vehicle, the receiving sleeve advantageously protrudes backwards from the retainer insertion projection. A substantially right-angled or L-shaped arrangement of retainer insertion projection and receiving sleeve is realised, for example. An insertion section or insertion arm of the load carrier or of the coupling part having the coupling insertion projection can be short, for example.

In the state of being mounted on the vehicle, the receiving sleeve advantageously protrudes from a bumper or rear end of the motor vehicle.

Furthermore, it is advantageous if an insertion opening of the receiving sleeve in the state of being mounted on the vehicle protrudes backwards and/or freely from a bumper of the vehicle. This measure means that the coupling part or the load carrier can be easily inserted into the receiving sleeve.

Advantageously, the retainer part can also have multiple parts and a base part as well as a receiving part, which can be connected to each other using flange parts. The flange parts support each other with supporting surfaces and can be screwed together by means of a screw assembly.

The receiving part can be fitted on the base part preferably at least two different distances in relation to a road surface. The supporting surfaces or at least one supporting surface, advantageously the supporting surface of the flange part of the base part, have in terms of the longitudinal extension thereof such a length that the respective other flange part can be fitted on said flange part in two longitudinal mounting positions, and the receiving sleeve or that the receiving part bearing the receiving sleeve can be fitted on the base part at least two different distances from a road surface.

Advantageously, provision is made that the receiving sleeve is supported on the rear side thereof by a flange part opposite to an insertion opening for the coupling insertion projection.

