Abstract:
In the case of a trailer coupling for motor vehicles, including a cross member, which is connectable to a motor vehicle body, and a bearing unit, which carries a ball neck that at a first end is connected to the bearing unit and at a second end carries a coupling ball, and a holding base, which carries the bearing unit and is connected to the cross member, it is proposed according to the invention that the holding base should have a flange unit, for receiving the bearing unit, and two holding elements that project from the flange unit and in so doing run at a spacing from one another and act on the cross member.

Description:
CROSS-REFERENCE TO RELATED PATENT APPLICATIONS 
     This patent application claims the benefit of German application No. 10 2015 100 490.9, filed Jan. 14, 2015, the teachings and disclosure of which are hereby incorporated in their entirety by reference thereto. 
     BACKGROUND OF THE INVENTION 
     The invention relates to a trailer coupling for motor vehicles, including a cross member, which is connectable to a motor vehicle body, and a bearing unit, which carries a ball neck that at a first end is connected to the bearing unit and at a second end carries a coupling ball, and a holding base, which carries the bearing unit and is connected to the cross member. 
     Trailer couplings of this kind are known from the prior art, for example EP 2 261 066. 
     These trailer couplings have the problem that the holding base is to be produced with as much stability and at as low a cost as possible. 
     SUMMARY OF THE INVENTION 
     This problem is solved according to the invention in the case of a trailer coupling of the type mentioned in the introduction in that the holding base has a flange unit, for receiving the bearing unit, and two holding elements that project from the flange unit and in so doing run at a spacing from one another and act on the cross member. 
     The advantage of the solution according to the invention is that the holding elements that run, projecting from the flange unit, at a spacing from one another and act on the cross member make possible a connection between the bearing unit and the cross member that is stable and in particular resistant to bending and low in cost. 
     In principle, it would be conceivable for the holding base to be composed from the flange unit and the holding elements. 
     A solution that, from the point of view of production, is particularly advantageous provides for the holding base to be formed by two elements made from flat material, each of which includes a flange element that contributes to the formation of the flange unit, and each of which forms one of the holding elements that extend, projecting from the flange unit, in the direction of the cross member. 
     The flange elements could for example be arranged separated by spacer elements for formation of the flange unit. 
     It is particularly favourable if the flange unit comprising the flange elements is formed such that the flange elements abut against one another by means of mutually facing abutment sides. 
     A solution of this kind has the advantage that, because of the structure of the flange unit comprising two flange elements, it has the effect that a stable flange unit is producible in a simple manner. 
     Further, it is preferably provided for each of the holding elements to be firmly connected to the respective flange element and in this way for the stable connection to be made between the cross member and the respective flange element. 
     In this arrangement, the holding elements could be connected to the respective flange element by positive locking or by joining. 
     A particularly advantageous solution provides for each of the holding elements to merge in one piece with the respective flange element such that as a result each holding element having the associated flange element is producible in a particularly simple and thus low-cost manner. 
     Advantageously, each of the holding elements is arranged in relation to the corresponding flange element such that it merges with the respective flange element by way of a bend region. 
     No statements have yet been made as regards the alignment of the holding elements in relation to one another. 
     Thus, a particularly favourable solution provides for the holding elements to run at an increasing spacing from one another as the spacing from the flange unit increases. 
     A preferred solution provides for the respective holding elements to extend at an increasing spacing from a centre plane of the flange unit as the extent away from the flange unit increases. 
     Preferably, the centre plane of the flange unit is defined as the geometric plane that runs between the flange elements—which for example abut against one another—in the flange unit. 
     A structurally particularly simple solution provides for the holding elements to be bent around along a bend line in relation to the corresponding flange elements such that a path of the holding elements in relation to the centre plane is produced in which the holding elements, projecting from the bend line, also extend at an increasing spacing from the centre plane as the extent away from the bend line increases. 
     In the simplest case, both the flange element and the holding element are formed from a planar piece of flat material and consequently lie at an angle to one another. 
     In this arrangement, in a particularly simple case, the holding elements lie at an acute angle to a centre plane of the flange unit. 
     In particular, the holding element and the respective flange element of the respective element form an obtuse angle with one another. 
     In this arrangement, it is provided for example for the obtuse angle between the holding element and the respective flange element to be in the range between 100 degrees and 170 degrees and preferably in the range between 120 degrees and 160 degrees. 
     In order to achieve the optimum possible stability, it is preferably provided for a projection of the bend lines of the elements onto the centre plane to result in an intersecting path of the projected bend lines—that is to say for the bend lines projected onto the centre plane to run transversely to one another. 
     In particular, in this arrangement it is provided for the projected bend lines to form an acute angle with one another that is for example in the range between 15 degrees and 140 degrees, preferably in the range between 40 degrees and 100 degrees. 
     Because the projected bend lines run transversely to one another in the centre plane, the holding base produced from the two elements having the flange elements and the holding elements is particularly resistant to bending and twisting, since in each case one of the elements counters a flexural elastic behaviour of the other of the elements. 
     More detailed statements have not yet been made as regards the connection between the holding elements and the cross member. 
     In principle, it would be conceivable to join the holding elements for example to the cross member by screwing or adhesion. 
     However, a particularly favourable solution provides for the holding elements to be welded to the cross member. 
     A stable connection between the holding elements and the cross member is in particular achievable if the holding elements abut against an outer peripheral surface of the cross member. 
     In this arrangement, in particular the holding elements are provided with cross member receptacles that abut against the outer peripheral surface of the cross member. 
     The cross member receptacles preferably take the form of cutouts provided in the holding elements such that in the region of the cross member receptacles the holding elements extend transversely to the cross member, in particular at an angle other than 90°. 
     In particular, the cross member receptacles are formed by edge contours, delimiting the cutouts, of the holding elements that abut against the outer peripheral surface of the cross member. 
     In this arrangement, in theory the cross member receptacles could abut against the outer peripheral surface of the cross member in individual regions. 
     However, a particularly advantageous solution provides for the cross member receptacles to abut against the outer peripheral surface along their edge contours. 
     In order, in this arrangement, to provide a stable connection to the cross member, it is preferably provided for the cross member receptacles to engage around the outer peripheral surface of the cross member over an angular range of at least 120° in relation to a centre axis of the cross member. 
     Preferably, it is provided for the cross member receptacles to engage around the outer peripheral surface of the cross member over an angle of at least 150 degrees, and preferably at least 180 degrees. 
     Further, preferably the cross member receptacles are welded to the cross member linearly and along their edge contour. 
     A particularly stable embodiment of the holding base provides for the cross member receptacles to be arranged on the holding elements in regions having the greatest spacing from one another. 
     Further features and advantages of the invention form the subject matter of the description below and of the illustration of an exemplary embodiment in the drawing. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  shows a perspective and partly cut-away view of a motor vehicle having a trailer coupling according to the invention; 
         FIG. 2  shows a perspective illustration of a first exemplary embodiment of the trailer coupling according to the invention; 
         FIG. 3  shows a view of the trailer coupling in the direction of the arrow A in  FIG. 2 ; 
         FIG. 4  shows a view in the direction of the arrow B in  FIG. 2 ; 
         FIG. 5  shows a view in the direction of an arrow C in  FIG. 2 , and in the operative position; 
         FIG. 6  shows a view of a cross member with a holding base, in the direction of the arrow D in  FIG. 2 ; 
         FIG. 7  shows a section along the line  7 - 7  in  FIG. 6 ; 
         FIG. 8  shows an enlarged view of the holding base in the direction of the arrow E in  FIG. 6 ; 
         FIG. 9  shows an enlarged view of the holding base in the direction of the arrow F in  FIG. 8 ; 
         FIG. 10  shows a view of the holding base in the direction of the arrow G in  FIG. 9 ; 
         FIG. 11  shows a section along the line  11 - 11  in  FIG. 10 ; and 
         FIG. 12  shows a plan view of the holding base and the part of the cross member carrying the latter, in a second exemplary embodiment. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     A motor vehicle that is designated  10  as a whole in  FIG. 1  includes a vehicle body  12 , on which there is mounted in a rear region  14  a trailer coupling  20  according to the invention that has a cross member  22 , which is covered by a bumper unit  16  and extends transversely to a longitudinal direction  18  of the vehicle body  12  and transversely over the rear region  14 , and side supports  24 , which extend approximately parallel to the longitudinal direction  18  of the motor vehicle  12  along body wall portions  26  and are fixed thereto and which, together with the cross member  22 , form a holding unit  28  that is covered partly by the vehicle body  12  and partly by the bumper unit  16 . 
     Provided on the holding unit  28  is a holding base  32  of a bearing unit that is designated  30  as a whole, for example a pivot bearing unit, to which a ball neck that is designated  40  as a whole is connected by means of a first end  42 , this ball neck moreover carrying at a second end  44  a coupling ball that is designated  46 , as illustrated in  FIGS. 1 and 2 . 
     The pivot bearing unit  30  provides the possibility of pivoting the ball neck  40  from an operative position A, which is illustrated in  FIGS. 2 and 3  and in which a ball centre axis  48  of the coupling ball  46  lies on a vertical vehicle longitudinal centre plane FL that is parallel to the longitudinal direction  18 , about a pivot axis  50  that runs transversely, in particular obliquely and preferably at an acute angle to the vehicle longitudinal centre plane FL, into a rest position R that is illustrated in  FIG. 3 , in which a centre portion  52  of the ball neck extends transversely to the vehicle longitudinal centre plane FL and the coupling ball  46  lies laterally with respect to the vehicle longitudinal centre plane FL, as illustrated in  FIG. 3 . 
     In particular, in this arrangement the ball neck  40  in the rest position R is arranged in a position that is covered by the bumper unit  16  of the vehicle body  12 , laterally with respect to the vehicle longitudinal centre plane FL. 
     With such an arrangement of the pivot axis  50 , in particular there is the possibility of arranging the ball neck  40  in the rest position on a side of the coupling ball  46  remote from a road surface  54 , as illustrated in dashed lines in  FIG. 3 . 
     There is at least the possibility of arranging the ball neck  40  in the rest position at a spacing from the road surface  54  such that it is higher up than a lower edge  56  of the bumper unit  16 , in relation to the course of the road surface  54 . 
     As illustrated in  FIGS. 3 to 11 , the holding base  32  includes a flange unit  62 , on which the pivot bearing unit  30  is mounted, and holding elements  64  and  66  that extend in a manner projecting from the flange unit  62  and, as illustrated in  FIGS. 3 to 11 , in projecting from the flange unit  62  extend increasingly far away from one another and in particular, projecting from a geometric centre plane  68  of the flange unit  62 , run at an increasing spacing from the centre plane  68  as the spacing from the flange unit  62  increases, as illustrated in  FIGS. 6 and 9 . 
     Preferably, as illustrated in  FIGS. 5 and 6 , the geometric centre plane  68  runs obliquely with respect to a centre axis  128  of the cross member  22  in the region of the cross member  22  that carries the holding base  32 , as illustrated in  FIG. 6 . 
     In particular, in this arrangement the holding base  32  is formed by two elements  74  and  76  made from flat material, which have two flange elements  84  and  86  that abut against each other for example by means of mutually facing abutment sides  94  and  96 , wherein the abutment sides  94  and  96  each border the centre plane  68  of the flange unit  62  such that both abutment sides  94  and  96  are ultimately arranged bordering on the geometric centre plane  68 . 
     Projecting from the flange element  84 , the element  74  includes the holding element  64 , which is bent in relation to the flange element  84  along a bend line  104  and thus, projecting from the bend line  104 , at an angle to the centre plane  68 , and runs at an increasing spacing from the centre plane  68  as the spacing from the bend line  104  increases. 
     Preferably, in this arrangement, the holding element  64  is also a part made from the flat material from which the element  74  is formed, with the result that—as illustrated in  FIGS. 8 to 11 —the flange element  84  and the holding element  64  are each flat material parts that merge with one another in one piece by way of a bend region  102  predetermined by the bend line  104 , wherein the flat material parts form with one another an obtuse angle α that is in the range between 100 degrees and 170 degrees. 
     The acute angle β at which the holding element  64  runs in relation to the abutment side  94  and thus to the centre plane  68  is in the range between 10 degrees and 80 degrees, preferably in the range between 20 degrees and 60 degrees. 
     The holding element  66  is also—as illustrated in  FIGS. 8 and 9 —part of the element  76  that includes the flange element  86 , relative to which the holding element  66  runs at an angle, projecting from a bend line  106 . 
     The element  76  is also formed from flat material, wherein the flange element  86  and the holding element  66  merge with one another by way of a bend region  108  predetermined by the bend line  106  and the flat material parts form with one another an obtuse angle that is also in the range between 100 degrees and 170 degrees. 
     In particular, the holding element  66  runs in relation to the abutment side  96  of the flange element  66 , projecting from the bend line  106  at an angle in the range between 10 degrees and 80 degrees, preferably in the range between 20 degrees and 60 degrees. 
     Thus, the holding element  66  also runs from the bend line  106  at an acute angle in relation to the centre plane  68 . 
     As can be seen from the projection according to  FIG. 8 , the bend lines  104  and  106  do not run parallel to one another but rather their projection onto the centre plane  68 , which in  FIG. 6  is represented by the plane of the drawing, produces an acute angle γ between the bend lines  104  and  106  that is in the range between 15 degrees and 140 degrees, preferably in the range between 40 degrees and 100 degrees. 
     The flange elements  84  and  86  are for their part provided with identically arranged apertures  112 , which are arranged around the pivot axis  50 , preferably on a circular line around the pivot axis  50 , and serve to receive mounting screws by means of which the pivot bearing unit  30  is mountable on the flange unit  62 . 
     In principle, it would be conceivable to connect the flange elements  84  and  86  to one another, for example by spot welding or by adhesion over a surface. 
     A connection of this kind is not necessary, however, since screws  113  that pass through the apertures  112  for mounting the pivot bearing unit  30  at the same time clamp the two flange elements  84  and  86  to one another such that the latter are firmly connected to one another by the mounting of the pivot bearing unit  30  to the flange unit  62 . 
     For connection to the cross member  22 , the holding elements  64 ,  66  are provided with cross member receptacles  114 ,  116  ( FIGS. 7 to 9 ), which are created by portions cut out of the flat material that forms the holding elements  64 ,  66 , wherein the course of edge contours  124 ,  126  of the cross member receptacles  114  and  116  that are formed by the cutouts is adapted to an outer peripheral surface  118  of the cross member  22  against which the cross member receptacles  114  and  116  preferably abut linearly by means of their edge contours  124  and  126  and are welded to the cross member  22  along the linearly abutting edge contours  124  and  126 , wherein preferably a linear weld connection is produced. 
     Preferably, the cross member receptacles  114  and  116  are formed such that, as illustrated in  FIGS. 6 and 7 , they engage around the outer peripheral surface  118  of the cross member  22  in a peripheral region that extends over more than an angular range of 120 degrees about a centre axis of the cross member, preferably an angular range of more than 150 degrees about the centre axis  128  of the cross member  22 . 
     The holding base  32  according to the invention on the one hand, as a result of the holding elements  64  and  66  that run in a manner diverging from one another, permits a stable connection that is in particular resistant to bending between the holding base  32  and the cross member  22 , and is moreover producible in a simple manner in that it includes two elements  74  and  76  made from a plate-shaped flat material in which in each case the holding element  64 ,  66  is bent away in relation to the flange element  84  and  86  forming the flange unit  62  along a bend line  104 ,  106 , in order on the one hand to obtain, in the case of for example mutually abutting flange elements  84  and  86  that are connected to one another to form the flange unit  62 , the divergent path of the holding elements  84  and  86 . 
     In a second exemplary embodiment of a trailer coupling according to the invention, the holding base  32 ′ includes a flange unit  62 ′ that is formed from more than two, for example four, elements  74 ′,  75 ′,  75 ′ and  77 ′ made from flat material, wherein each of the elements  74 ′ to  77 ′ has a holding element  64 ′,  65 ′,  66 ′ and  67 ′ and a corresponding flange element  84 ′,  85 ′,  86 ′,  87 ′. 
     All the flange elements  84 ′,  85 ′,  86 ′,  87 ′ run parallel to the centre plane  68 ′ and in particular abut flat against one another in order to form the flange unit  62 ′ that carries the bearing unit  30 . 
     The holding elements  64 ′,  65 ′,  66 ′ and  67 ′ form an obtuse angle with the flange elements  84 ′,  85 ′,  86 ′,  87 ′. 
     In particular, in the second exemplary embodiment as illustrated in  FIG. 11  as well, the holding elements  64 ′,  65 ′,  66 ′,  67 ′ run at an increasing spacing from one another as the spacing from the flange unit  62 ′ increases. 
     Otherwise, in the second exemplary embodiment the features that have not been mentioned separately are identical or similar to those of the first exemplary embodiment, so reference can be made in full to the statements regarding the first exemplary embodiment.