Abstract:
A roller blind cassette for receiving a roller blind shaft and a roller blind which in the stowed state is wound onto the roller blind shaft and in a functional state is drawn in a longitudinal direction through an exit slot of the roller blind cassette. The cassette has a housing with a hollow section slotted along its length and extending in a direction transverse to the longitudinal direction and forming the exit slot of the roller blind cassette. Two opposite edge regions extend on both sides of the slot of the hollow section and are connected to one another in the region of two opposite ends of the hollow section by a connecting bridge.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This is a divisional of prior U.S. application Ser. No. 13/422 443, filed Mar. 16, 2012, which claims the priority of German Application No. 10 2011 005 819.2, filed Mar. 18, 2011, the disclosure of which applications are hereby incorporated by reference in their entirety into this application. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The invention relates to a roller blind cassette for receiving a roller blind shaft and a roller blind which in the stowed state is wound onto the roller blind shaft and in a function state can be drawn in a longitudinal direction off the roller blind shaft through an exit slot of the roller blind cassette, having a housing which has a hollow section slotted along its full length and extending in a main extension direction transversely to the longitudinal direction and whose slot forms the exit slot of the roller blind cassette. 
       BACKGROUND OF THE INVENTION 
       [0003]    Generic roller blind cassettes are widely known from the prior art and are used for roller blinds in motor vehicles, for instance for roller shades or as covers for luggage compartments, in order to hold the wound roller blind when it is not necessary for it to be in its function state. The base element of such roller blind cassettes, which is formed as a slotted hollow section, is advantageous from a production engineering point of view when compared with a closed hollow section that is subsequently machined, since it involves a reduced machining effort and the costs can therefore be reduced. Slotted hollow sections of this type are however significantly less resistant to torsion than closed hollow sections, since their edges in the area of the slot provide little resistance to a relative displacement in the main extension direction. In known roller blind cassettes with a slotted hollow section, comparatively thick medium plate, in particular having walls thicker than 1.5 mm, is used to obtain an adequate resistance to torsion. Thinner walls have until now been regarded as disadvantageous, since they cannot ensure adequate resistance to torsion in the roller blind cassette. 
         [0004]    A disadvantage of these roller blind cassettes known from the prior art and having thick walls is that they have comparatively high mass. There is however a growing need to reduce the mass of every component used in a vehicle in order to increase its efficiency. A reduction in the mass is also desirable for roller blind cassettes. 
       SUMMARY OF THE INVENTION 
       [0005]    The object of the invention is therefore to further develop a generic roller blind cassette such that it has a low mass while being adequately resistant to torsion. 
         [0006]    In accordance with the invention, this is achieved in accordance with a first aspect of the invention in that two edge regions opposite one another and extending in the main extension direction on both sides of the slot of the hollow section are connected to one another in the region of two opposite ends of the hollow section by a connecting bridge, with this connecting bridge being connected to at least one of the edge regions by connecting means that counter in a positive manner the freedom of the connecting bridge to rotate at the edge region transversely to the main extension direction of the roller blind cassette. 
         [0007]    In accordance with the invention, it is therefore provided that the edge regions of the cassette are directly connected to one another, this connection being implemented by a connecting bridge in such a way that the connecting bridge is fastened at at least one edge in such a way that it cannot twist around a rotational axis aligned transversely to the main extension direction, since this would counter the desired resistance to torsion. Preventing the freedom to rotate at both the edge regions that are connected to one another by the connecting bridge is advantageous but not strictly necessary, since the rotary fixing mentioned above of the connecting means at one edge region achieves fixing that makes it possible to design the fixing on the other side more simply. An edge region is understood in the meaning of this invention to be a region that is not more than 15 mm away from the slot in the hollow section, and preferably not more than 10 mm. At least part of the transfer of force from the hollow section into the connecting bridge takes place within this edge region. 
         [0008]    The connection as described of the opposed edge regions by means of a connecting bridge can achieve a significant increase in the resistance to torsion, so it is no longer necessary to use very thick plate materials. The mass can therefore be reduced. 
         [0009]    Particularly simple designs of the connection between the roller blind cassette and the connecting bridge can be achieved if screwed or riveted joints are used here, where two such screws or rivets should be provided in such cases at at least one of the two ends in order to provide a positive prevention of the freedom to rotate. 
         [0010]    In an alternative embodiment, which is particularly advantageous from the point of view of easy assembly, the connecting means used to connect the connecting bridge to the hollow section incorporate a receiving shaft in the edge region of the housing and formed by the housing, into which an insertion piece on the connecting bridge, preferably made in one piece therewith, is inserted in the main extension direction. In such a design, therefore, suitable shaping of the hollow section forms a receiving shaft that extends in the main extension direction and into which is inserted an insertion piece of the connecting bridge that also extends in the main extension direction. It is possible here for the receiving shaft and the insertion piece to have a constant cross-section along their length. It is however advantageous for the insertion piece to taper slightly towards its more remote end, so that when the insertion piece is fully inserted there is also a non-positive coupling between the housing and the insertion piece with respect to a relative movement in the main extension direction. It is furthermore advantageous with this design when receiving shafts of this type are provided on both sides of the slot, and when the connecting bridge incorporates two substantially parallel insertion pieces that are pushed into these receiving shafts at the two opposite edge regions. 
         [0011]    The aforementioned taper allows a press-fit connection to be created which counters non-positively any withdrawal of the connecting bridge from the receiving shafts or from the at least one receiving shaft. Positive prevention of withdrawal is advantageous. This can, for instance, be formed by a connecting screw, connecting pin or connecting rivet passing through the hollow section in the region of the receiving shaft and through the insertion piece. In a particularly advantageous embodiment however, positive fastening means are provided on the hollow section and the insertion piece, in particular in order to create a snap connection by means of which the insertion piece is secured in the receiving shaft to prevent withdrawal. These fastening means are preferably designed such that they achieve a secured state simply by insertion of the insertion piece into the receiving shaft. The method of operation can here be that of a barbed hook. This results in a very simple assembly process, since it is only necessary to bring the connecting bridge with the insertion piece that is moulded onto it from the side up to the hollow section and to push it in to create the desired connection. A specific design of the fastening means could however provide that recesses or depressions are provided in the hollow section on the inside of the receiving shaft, into which a tongue provided on the insertion piece can be snapped as soon as the insertion piece has been introduced far enough into the receiving shaft. A complementary design in which the recess or the depression is provided on the insertion piece while the tongue is formed on the hollow section is equally effective. 
         [0012]    To create the receiving shaft, it is preferably provided that the edge region of the hollow section is folded over on both sides of the slot in the edge region adjacent to the slot, thereby creating slot-like receiving shafts on both sides. 
         [0013]    The connecting bridge can be designed such that it merely provides the connection between the two opposite edge regions, but nevertheless leaves the ends of the hollow section unclosed. It can however also be effective if the connecting bridge is made in particular in one piece with an end cap closing off the end of the hollow section and at least to a large extent closing the open end of the housing. In such a design, the connecting bridge thus performs a double function. It is the support for the end wall of the housing that is fastened to or moulded on it, and at the same time stabilizes the housing to prevent torsion. The end wall can at the same time also have the purpose of being the bearing location for the roller blind shaft rotatably mounted inside the housing. 
         [0014]    The invention furthermore relates to a designed related to the design as described above, where a generic roller blind cassette is further developed such that a connecting bridge extends over the slot from at least one edge region to at least one of the ends and is made in one piece with the hollow section and whose more remote end is fastened to the opposite region. Alternatively, connecting bridges can extend over the slot from both the opposite edge regions to at least one end of the hollow section, each bridge being made in one piece with the hollow section, and whose more remote ends are connected to one another. 
         [0015]    With such a design, a separate connecting bridge is therefore omitted. Instead, one or two connecting bridges made in one piece with the hollow section are used at each end. If only one such connecting bridge is used at each end, it extends over and past the slot, and is connected on the opposite side to the edge region in that area in such a way that a relative movement of the connecting bridge with respect to the edge region in the direction of the main extension direction is prevented. In this way, the desired resistance to torsion is again achieved. The fastening used there is preferably a positive one, which again can be formed using a screwed or riveted connection passing through the connecting bridge and the hollow section. In the design with two connecting bridges at each end that extend from the opposite sides towards each other, this connection is flush with the slot. 
         [0016]    This design again achieves a high level of resistance to torsion which also, due to the material bond arising from the connecting bridge being in one piece with the hollow section, can offer even greater stability than when an entirely separate connecting bridge is used. 
         [0017]    The minimum of one connecting bridge at each end is preferably formed by making a cut in the hollow section transversely to the main extension direction, by which cut the connecting bridge is separated from a folded edge region of the exit slot. This makes it possible during manufacture, after making this cut extending transversely to the main extension direction, to fold over the edge region(s) in the area where the exit slot is to be formed, with the connecting bridge(s) remaining unaffected by this as a result of the cut. This makes it easy to manufacture. 
         [0018]    A roller blind cassette in accordance with the invention is preferably a roller blind cassette made of metal, in particular made from metal plate of constant thickness. In order to achieve a low mass, this thickness is preferably no more than 1.5 mm, and in particular preferably no more than 1 mm. As is made clear above, this low wall thickness of the hollow section can be sufficient thanks to the resistance to torsion achievable with the connecting bridge. The connecting bridge itself is, even when it is provided as a separate component, also preferably made of metal. Here again this is preferably a metal plate component which is given the desired form through by or a similar process so that, for instance, an insertion piece of the type described above can be formed in this way. 
         [0019]    The roller blind cassette in accordance with the invention is used in a roller blind in accordance with the invention which is in particular provided and designed for use in a vehicle. This roller blind comprises, in addition to the roller blind cassette in accordance with the invention, a roller blind shaft rotatably mounted inside the roller blind cassette along with a roller blind which is wound onto the roller blind shaft and which can be wound off the roller blind shaft. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0020]    Further advantages and aspects of the invention emerge not only from the claims but also from the description below of preferred embodiments of the invention, which are explained in more detail. Shown here in 
           [0021]      FIGS. 1   a  and  1   b  illustrate a first embodiment of a roller blind cassette in accordance with the invention with a separate connecting bridge, 
           [0022]      FIG. 2  illustrates a second embodiment of a roller blind cassette in accordance with the invention with a separate connecting bridge, 
           [0023]      FIG. 3  illustrates a third embodiment of a roller blind cassette in accordance with the invention with a separate connecting bridge, 
           [0024]      FIGS. 4   a  and  4   b  illustrate a fourth embodiment of a roller blind cassette in accordance with the invention with a separate connecting bridge, 
           [0025]      FIGS. 5   a  and  5   b  illustrate a fifth embodiment of a roller blind cassette in accordance with the invention, which represents a variation on the embodiment of  FIGS. 4   a  and  4   b , and 
           [0026]      FIGS. 6   a  and  6   b  illustrate a sixth embodiment of a roller blind cassette in accordance with the invention with a moulded-on connecting bridge, 
       
    
    
     DETAILED DESCRIPTION 
       [0027]      FIGS. 1   a  and  1   b  illustrate schematically a first embodiment of a roller blind cassette in accordance with the invention. This roller blind cassette  100  primarily comprises an open, hollow section  110  designed as a curved piece of metal plate. The thickness of the walls of this hollow section is in the region of 1 mm. As a result of being made as an open hollow section, it is easy and economical to fabricate. Nevertheless, an open and hollow section such as this has a tendency to twist markedly if subjected to the torsion indicated by the arrows  2   a,    2   b . The resultant movement of the hollow section  110  in the longitudinal direction is illustrated by the arrows  3   a  and  3   b.  In order to prevent this, connecting bridges  120  are provided at both of the ends  110   a,    110   b  of the hollow section  110 , where for the sake of clarity only the connecting bridge on the left-hand side is illustrated in the embodiments of  FIGS. 1 to 5 . 
         [0028]    In the case of the embodiment of  FIGS. 1   a  and  1   b , the connecting bridge  120  is a simple strip of metal plate. This is, as illustrated in  FIG. 1   b , mounted on the inside in the region of a slot  112  of the hollow section  110 , and connected to the edge regions  112   a,    112   b  on both sides of the slot by means of rivets  130 . Here, at least in one edge region  112   a,  two holes  114   a  are provided for these rivets  130 , so that after the connecting bridge  120  has been fastened as shown in  FIG. 1   b,  the connection is fixed, and in particular fixed so that it cannot rotate, relative to the edge region  112   a.  In the edge region  112   b  on the opposite side, in the embodiments of FIGS. la and lb, only one rivet  130  is provided to connect the hollow section  110  to the connecting bridge  120 . It is of course possible to improve the force transfer by providing a second rivet here as well. 
         [0029]    The hollow section made in this way to hold a roller blind shaft  102  illustrated in  FIG. 1   b,  and whose purpose is to wind up a roller blind  104 , can be made economically and is exceptionally stable. It is therefore an economical alternative to what was originally a closed hollow section, in which the outlet slot is created after the hollow section has been manufactured. 
         [0030]    The embodiment of  FIG. 2  illustrates how the connecting bridge  120  does not necessarily have to be made as a simple, plane connecting strip. Instead it can be shaped in such a way that it partially or fully closes the open cross-section found at the ends  110   a,    110   b  of the hollow section. In such a case, it is advantageous if the end wall  120   a,  which is preferably made in one piece with the connecting bridge, also has on its inner face bearing means, not illustrated, for mounting of the winding shaft  102 . 
         [0031]      FIG. 3  illustrates that the stabilization of the open, hollow section by means of a connecting bridge  120  is not restricted to cassettes in which the edge regions  112   a ,  112   b  are aligned with one another on both sides of the slot  112 . Instead, it is quite possible for the slot  112  to be located in an exposed position between two edge regions  112   a,    112   b  that are angled relative to one another. In such a case, the connecting bridge  120  is provided as a curved component in the manner shown in  FIG. 3 . 
         [0032]      FIGS. 4   a  and  4   b  illustrate a further embodiment of a roller blind cassette  200  in accordance with the invention. In this, connecting means separate from the hollow section  210  and the connecting bridge  220  are not used. Instead, the hollow section  210  is folded over in the region of the slot  212  at each of the edge regions  212   a  and  212   b,  so that two receiving shafts  216  are formed at the two ends  210   a,    210   b.  Correspondingly, the connecting bridge  220  is provided with two insertion pieces  222  extending approximately in the main extension direction  1  of the roller blind cassette  200  and slightly tapering towards their more remote end. In this embodiment, these approximately U-shaped connecting bridges  220  are pushed at both ends of the slot  212  into the receiving shafts  216 . The receiving shafts  216  and the insertion pieces  222  are here matched to one another such that a permanent non-positive press-fit is created to counter torsion of the roller blind cassette  200 . In order to create an adequate press-fit, it is however necessary to push the insertion pieces  222  into the receiving shafts  216  with considerable force. 
         [0033]    The embodiment of  FIGS. 5   a  and  5   a  is related to this, but has insertion pieces  222  which have engaging thickened portions  222   a  on their upper faces. These have a vertical face on their outward-looking sides, and—taking  FIG. 5   a  as a reference—extended sloping faces on the ends facing towards the receiving shaft  216 . Corresponding to these, recesses  218  are provided in the edge regions  212   a ,  212   b  on both sides of the slot  212 , into which the thickened portions  222   a  can engage. 
         [0034]    When assembling the roller blind cassette according to  FIGS. 5   a  and  5   b , considerably less force is therefore necessary in comparison with assembling the embodiment of  FIGS. 4   a  and  4   b . As soon as the two insertion pieces  222  of the connecting bridge  220  are pushed far enough into the receiving shafts  216 , the engaging thickened portions  222   a  snap into the recesses  218 , and, in the manner of a barbed hook, effectively prevent a relative movement in opposite directions between the edge regions  212   a  and  212   b.  High torsional stiffness of the roller blind cassette  200  is again the result. 
         [0035]    There is no separate connecting bridge in the embodiment according to  FIG. 6   a . The edge regions  312   a ,  312   b  are instead folded over in a similar manner to the embodiment of  FIGS. 4 and 5 . In the regions of each of the two ends  310   a,  however, a cut  313  is made, as a result of which the connecting bridges  315   a,    315   b  are left out of the folding process. These therefore extend substantially in the same plane as the edge region  312   a  and  312   b,  and overlap one another. In the region of the overlap, they are connected to one another by a connecting means, here taking the form of a rivet  330 . The torsional stiffness achieved in this way is greater even than the torsional stiffness of the foregoing embodiments, since, due to the forming of the connecting bridges  315   a,    315   b  in one piece with the hollow section  310 , there is no reason to expect the connecting bridges to separate from the hollow section  310 . 
         [0036]    In an alternative embodiment, not shown in the drawing, a connecting bridge is only formed on one of the two sides, extending toward the opposite side. On the far side of the exit slot, this overlaps the opposite edge region and is again fastened there by a connecting means such as a rivet.