Abstract:
In a motor vehicle with a roof opening ( 12 ) located in a fixed roof surface ( 10 ) and a cover ( 13 ) for closing the roof opening, the cover has an at least partially transparent pane ( 14 ) and a frame which is connected to the pane and which extends over at least one part of the edge of the pane. The pane ( 14 ) is a plastic pane and the frame is formed by in situ foaming ( 20 ) of a foam material onto the periphery of the pane, the shape of the pane, in at least one partial area of a connecting region between the pane and the peripheral foam, is configured such that a permanent mechanical, positive interlocking connection is created between the pane and the peripheral foam.

Description:
BACKGROUND OF THE INVENTION  
   1. Field of the Invention 
   This invention relates to a motor vehicle roof with a roof opening located in a fixed roof surface and a cover for closing the roof opening, the cover comprising at least one partially transparent pane and a frame which is connected to the pane and which extends over at least one part of the edge of the pane. 
   2. Description of Related Art 
   In these motor vehicles roofs, which can be roofs with a fixed or movable cover, the pane is conventionally a glass pane which is connected by means of a peripheral frame to the motor vehicle roof itself or to a positioning mechanism for positioning the cover. The frame can, moreover, be formed by foaming the pane in place, into which cover a metallic reinforcing or holding frame, for example, inner metal cover sheet, is inserted. 
   Aside from the glass elements, plastic panes which are cemented to a frame surrounding the pane are furthermore used in vehicle construction, especially for fixed elements. 
   While glass panes are advantageous in that they can be more easily worked, especially using techniques of foaming in place, it is however disadvantageous that glass covers have considerable inherent weight; this is disadvantageous not only with respect to the total weight of a roof structure, but especially when the cover is a movable cover which then requires a more complex configuration of the components supporting the cover and of the drive of the cover. 
   Plastic covers are lighter than glass covers, but much more difficult to install than the latter. This is due to the fact that the plastics used for producing vehicle roof covers generally have coefficients of thermal expansion which are very different from those of the metallic reinforcing and holding frame, and therefore, require corresponding movable connections between the pane and the frame, as is explained, for example, in German Patent DE 101 08 527 and corresponding U.S. Patent Application Publication 2002/0113466. 
   Instead of a corresponding movable mechanical connection, the attempt was made to connect the plastic cover by means of a material connection to the respective frame. For plastic covers using conventional materials, such as polycarbonates, to achieve the stability and durability of the cover required in motor vehicle construction, additional layers of hard material are applied to the outside and inside of the cover and are generally detrimental to a connection to other materials. As a result, the foaming-in-place processes used for glass covers to date are not applicable to plastic covers, and when a plastic cover is cemented to the frame, especially due to the aforementioned major differences with respect to coefficients of thermal expansion, faults and breaks in the cement often occur. 
   SUMMARY OF THE INVENTION  
   In view of the aforementioned problems, a primary object of the present invention is to devise a motor vehicle roof of the initially mentioned type which, on the one hand, has a low total weight and is still stable and easy to produce. 
   This object is achieved in accordance with this invention in that, in a motor vehicle roof of the initially mentioned type, the pane is a plastic pane and the frame is formed by foaming the pane in place, the shape of the pane, in at least one partial area of the connecting region between the pane and the peripheral foam, being chosen such that provision is made for a permanent mechanical connection between the pane and the peripheral foam by means of a positive interlocking connection. In this way, the advantages of easier workability of glass covers can be combined with those of the lower weight of plastic roofs, as a result of the positive interconnection between the plastic pane and the peripheral foam, provision having been made for a permanent, reliable connection between the pane and peripheral foam which does not degrade due to external effects and especially thermal influences. 
   The positive interlocking provides for a permanent mechanical connection between the plastic pane and the peripheral foam under all operating conditions of the motor vehicle roof. Furthermore, since positive interlocking between the pane and peripheral foam arises from the shape of the pane itself, no additional production or installation steps are necessary to join the pane to the peripheral foam. Rather, the shape elements which provide for the positive interlocking between the pane and peripheral foam are molded integrally to the pane directly as the pane is molded. Then, if the correspondingly molded pane is placed in the foaming-in-place tool and is foamed in place, the peripheral foam material fills the corresponding shape elements and thus provides for positive interlocking between the pane and the peripheral foam. 
   In particular, the pane can have at least one recess engaged by the peripheral foam. Preferably, in this connection, the shape of the recess is chosen such that the peripheral foam extends behind it. These recesses can be provided in the edge area of the pane on its top and/or bottom and on the face. Furthermore, in this connection, it can be a series of individual recesses or one groove which runs along at least one region of the side edge. 
   Furthermore, the pane can have at least one elevation or a projection which is embedded in the peripheral foam. Preferably, the shape of the projection is chosen such that the peripheral foam extends behind it. This can be accomplished, for example, in that an essentially L-shaped or T-shaped projection is molded onto the pane which, when it is embedded in the peripheral foam, prevents not only displacement between the pane and the peripheral foam, but also prevents the pane and peripheral foam from moving away from one another. 
   In another version of the invention, the pane can have an undercut along at least part of its side edge, behind which the peripheral foam extends. This can be accomplished, for example, in that the pane has a recess or a groove along its side edge which is filled with foam material when the pane is foamed in place. 
   Additionally, along at least part of its side edge, the pane can be encompassed by the peripheral foam; in this case, the pane preferably has a reduced cross section in the part of its side edge encompassed by the peripheral foam, so that a flush roof surface can also be accomplished in the region of the peripheral foam. To reduce the cross section, the pane can have a chamfer, depression and/or a bevel in the part of its side edge in which it is encompassed by the peripheral foam. 
   It goes without saying that the aforementioned measures can all be combined with one another in any manner, the shaping of the pane which provides for a permanent mechanical connection between the pane and the peripheral foam by means of a positive interlocking connection being provided either in several individual regions of the pane, or it can be made as a geometry which extends essentially over the entire side edge region of the pane. 
   In another version of the invention, the pane can have an essentially transparent inner region and an essentially opaque edge area so that the areas of the pane in which the mounting elements of the pane are located are covered as seen from the outside and a uniform appearance of the pane results. The opaque edge area can be made, for example, as a blackened region or as a region which is matched in color to the roof surface. 
   Preferably in this connection, the essentially opaque edge area is molded integrally to the essentially transparent inner region. In particular, the pane can be formed as an essentially transparent pane onto the edge area of which a layer of essentially opaque plastic is molded in one piece. In this connection, the transparent pane can be made such that it essentially completely spans the roof opening, a layer of essentially opaque plastic being molded onto the bottom of the transparent pane. Specifically, the pane can be produced from an essentially transparent polycarbonate material onto the edge area of which a layer of, for example, black polycarbonate material which is essentially opaque is molded in one piece. While it would be fundamentally possible to color the edge area of the transparent plastic pane, for example, by applying a layer of paint, for stability reasons it is preferred that the pane be produced in a two-step production process in which, in a first working step, the actual pane is produced from a transparent material onto the edge area of which, then, an essentially identical, but differently colored material is molded, so that a uniform part results which, with respect to its stability and further workability, is equal to a pane produced from only one material. 
   As in known, plastic panes used in motor vehicle construction can be provided on its outer side, preferably also on its inner side, with an additional layer of hard material, for example, of polysiloxane in order to increase the abrasion and scratch resistance of the pane. Depending on the choice of the materials used, in this connection, the hard material layer can optionally also be used as an adhesive between the plastic pane and the peripheral foam. 
   Furthermore, a reinforcing frame, for example, an inside metal cover sheet, can be inserted into the peripheral foam, and in this connection, the outside edge of the inside metal cover sheet can be embedded in the peripheral foam, while the inside edge of the inside metal cover sheet rests against the bottom of the pane. In order to preclude creaking or rattling of the free inner edge of the inside metal cover sheet against the bottom of the pane, between the inner edge area of the inside metal cover sheet and the pane there can be a damping layer, for example, of a rubber, microcellular rubber or textile layer which is applied to the inside metal cover sheet by cementing or by dry coating. 
   If other attachments of metal or plastic are to be fastened to the cover, such as for example, screens, seals, antennas, cable channels, shade guides, drive cables or the like, they can be embedded directly in the peripheral foam. Alternatively or in addition, holding devices, such as threaded bushings, sleeves, retaining clips and other inserts for mounting these attachments can be embedded directly into the peripheral foam, or recesses for mounting of these attachments can be molded directly into the peripheral foam. If these attachments or holding devices for attachments are embedded in the peripheral foam, they can be inserted directly into the foaming tool during foaming and thus embedded in the peripheral foam. 
   The peripheral foam can be made from a polyurethane material in the known manner. 
   Preferred embodiments of the invention are detailed below with reference to the drawings. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS  
       FIG. 1  is a schematic view of the upper portion a vehicle; 
       FIG. 2  is a sectional view of the side edge area of the cover of the motor vehicle roof shown in  FIG. 1 ; 
       FIGS. 3 to 7  are views similar to  FIG. 2  of modified embodiments of the cover; 
       FIG. 8  is a top plan view of the cover shown in  FIG. 7 ; and 
       FIG. 9  is a view similar to  FIG. 2  of another modified embodiment. 
   

   DETAILED DESCRIPTION OF THE INVENTION  
   The vehicle shown in  FIG. 1  has a roof opening  12  in a fixed roof surface  10 . To close the roof opening, there is a cover  13  which, in the illustrated embodiment, can move along a roof-mounted frame  15 . This invention is used especially on roofs with fixed elements, on sliding roofs, sliding and raising roofs, spoiler roofs, externally guided sliding roofs and the like. 
     FIG. 2  shows the cover  13  from  FIG. 1  in the area of its side edge. The pane  14 , which covers the roof opening and which forms the actual cover, is formed of a transparent pane  16  which is made, for example, from transparent polycarbonate to which a strip  18  of nontransparent material, for example, black polycarbonate, is molded in one piece on its bottom. This pane can be produced by means of a two-stage molding process in which, for example, first a transparent material is placed in a corresponding molding tool, to which a layer of essentially the same, but differently colored material is then molded in a second step so that a one-piece pane of uniform material results. In its edge area, the pane  14  is foamed in place with peripheral foam  20 , for example, of a polyurethane material, the peripheral foam preferably peripherally surrounding the entire edge area of the pane  14 . 
   To support the pane  14  and to move it on a roof mechanisms (not shown), there is a frame which can be the inside metal cover sheet  22  as shown in  FIG. 2 , which is inserted into the foaming-in-place tool at the same time, preferably when the pane  14  is being foamed in place. In this way, the inside metal cover sheet  22  can be connected to the pane  14  by means of the peripheral foam  20  without other production or mounting steps being necessary for this purpose. 
   In the embodiment shown in  FIG. 2 , a positive interlocking connection between the pane  14  and the peripheral foam  20  is established by a chamfer  24  being provided on the transparent part  16  of the pane  14  along its lower edge side, so that after molding the opaque region  18  onto the transparent pane  16 , a groove is formed in the side edge of the pane  14 , preferably a peripheral groove, which fills with foam material when the pane  14  is being foamed in place. Analogously to the undercut of the pane  14  shown here, the pane could also have a groove in its transparent part  16 , or a groove which extends both into the transparent part  16  and also the nontransparent part  18 . In any case, the positive locking between the pane  14  and the peripheral foam  20  produces a strong mechanical link of the pane  14  to the peripheral foam  20  which effectively opposes detachment of the pane from the peripheral foam due to high mechanical or thermal stress. 
     FIG. 3  shows a modified embodiment of the cover  13  according to  FIG. 2 . Here, the pane  14  which has been formed from the transparent pane  16  and the opaque region  18  has a peripheral indentation  26  along its side edge which is filled with the foam material of the peripheral foam  20 . 
   In the embodiment of the cover  13  in accordance with the invention, as shown in  FIG. 4 , the pane  14  which is formed from the transparent plastic pane  16  and the opaque plastic region  18  molded to it in one piece has an edge area  30  with a reduced thickness. In addition, there is a recess  32  in the region with the reduced thickness  30  at a distance from the outside edge of the pane. The outside edge of the pane  14  is foamed in place with polyurethane material, the peripheral foam  20  surrounding the region with the reduced thickness  30  such that the top of the peripheral foam  20  runs flush with the top of the pane  14 . 
   Furthermore,  FIG. 4  shows a configuration of the pane  14  in which there is a projection  28  which extends down on its bottom and from which another projection  34  extends laterally, so that altogether a generally L-shaped projection is formed which is positioned in the foam tool such that the projection becomes embedded in the peripheral foam. As in the preceding embodiments, in the embodiment as shown in  FIG. 4 , the pane  14  can also be made such that there are shaping features which provide for positive interlocking with the peripheral foam  20 , here especially, the recess  32  and the L-shaped projection  28 ,  34 , in partial regions of the pane, or extending along the entire periphery of the pane. 
   Furthermore, the outside edge of the inside metal cover sheet  22  is embedded in the peripheral foam  20  so that the inside edge of the sheet metal rests against the underside of the pane  14 . In order to hide the inside metal cover sheet  22  from view from above, the region  18  of the pane produced from the opaque plastic extends just beyond the inside edge of the inside metal cover sheet  22 . Between the inside edge of the inside metal cover sheet  22  and the pane  14  there can also be a damping component  36  which prevents rattling or creaking which could be caused by relative motion between the pane and the inside metal cover sheet. This damping component  36  is preferably an elastic material applied to the top of the inside metal cover sheet  22 , for example, of rubber, microcellular rubber or textile materials, for example, dry coating of the top of the inside metal cover sheet  22 . 
     FIG. 5  shows another embodiment of a cover  13  in which the outside edge of the pane  14  is encompassed by the peripheral foam  20 . In order to provide space for the peripheral foam  20  around the edge, and still for an altogether flush surface of the cover  13 , along the outside edge of the pane  14  in its transparent part  16  there is a chamfer  38  which is filled with foam material  40  when the pane  14  is foamed in place. If additional attachments such as, for example, screens or shade guides are to be attached to the cover  13 , as is illustrated in  FIG. 5 , mountings for these attachments, for example, threaded bushings  52 , can be embedded directly in the peripheral foam  20 . The threaded bushing  52  was inserted into the foaming tool at the same time that the pane  14  was being foamed in place, without the necessity of additional mounting steps. 
     FIG. 6  shows another embodiment of the cover  13  in which the transparent pane  16  is made as a pane with an essentially uniform thickness, but in which the area  18  of opaque material molded in one piece onto the bottom has a T-shaped projection  48  which is embedded in the PU foam material  20 . Furthermore,  FIG. 6  shows an embodiment of the cover in which there is a receiver  42  in a lateral face of the peripheral foam  20  in order to attach a sealing element (not shown) to the cover as is known. These receivers, by means of which attachments such as seals, screens, etc. can be attached to the cover, can be molded in anywhere on the peripheral foam  20 . 
     FIGS. 7 &amp; 8  show a configuration of the cover  13  in which the positive interlocking between the pane  14  and the peripheral foam  20  is accomplished by a chamfer  38  which runs along the upper outside edge of the transparent pane  16 , and by a plurality of elevations  44  which are provided on the bottom of the pane  14  in its opaque area. As is shown in  FIG. 8 , in this connection the elevations  44  can be arranged in a row in succession with a uniform distance between each other and with respect to the side edge of the pane. 
   Two other measures for making providing a positive interlocking of the peripheral foam  20  and the pane  14  are shown in  FIG. 9 . In particular, in this connection, the upper side edge of the pane  14  is beveled in its transparent region  16 , the pane in the area of the bevel  46  being encompassed by the foam material  20 . Furthermore, on the bottom of the pane, there is a recess  50  within the opaque region with an inside cross section which is larger than its opening cross section and which is filled with foam material when the pane is foamed in place. It goes without saying that the recess  50  need not be located only within the opaque region, as in the illustrated example, but, since the pane  14  formed from the transparent pane  16  and the opaque  18  region forms an integral, one-piece component, can also extend into the transparent region  16 .  FIG. 9  also shows an embodiment of a cover  13  in which an attachment, here an antenna  54 , is embedded directly into the peripheral foam  20 . Because the antenna  54  is inserted easily into the foaming tool at the same time as the pane  14  is foamed in place, additional installation steps are eliminated. 
   Besides the above explained versions, numerous other shaping versions are possible, by means of which provision can be made for positive interlocking between the pane and the peripheral foam which then keeps the pane itself fixed on the peripheral foam in all three-dimensional directions when the pane is exposed to repeated high mechanical and thermal stresses. The above described measures can be combined with one another as desired in this connection.