Abstract:
A folding top mechanism of a folding roof for a convertible, which has side roof rods with a guide means for movable support of the front bow and of the middle bow and a canvas folding top which is attached to the front bow, and which can be moved into a rear lowered position to open the folding roof, with the front bow being pushed at least partially over or under the middle bow by the guide means.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention relates to a folding top mechanism of a folding roof for a convertible, which has side roof rods with a guide means for movable support of the front bow and of the middle bow and a canvas folding top which is attached to the front bow, and which can be moved into a rear lowered position to open the folding roof. 
     2. Description of Related Art 
     Published German Patent Application DE 197 34 671 A1 discloses a folding roof which has a front bow which is guided on a side frame of the folding top and a canvas folding top which is attached to the front bow and which is guided in sealing rails of the side top frame for displacement when the folding roof is opened and closed. To open the folding roof, the front bow on the frame of the folding top is pushed to the rear, entraining the canvas folding top and pushing it together into folds according to the lateral guides of the canvas folding top in the sealing rails. 
     SUMMARY OF THE INVENTION 
     The primary object of the present invention is to provide a folding top mechanism of the initially mentioned type which ensures a simple sequence of motions when the bows are moved with consideration of orderly folding of the canvas folding top. 
     This object is achieved in accordance with the invention in the aforementioned folding top mechanism in that the front bow can be pushed at least partially over or under the middle bow by the guide means. By moving over one another, the free section of the canvas folding top is pulled to the rear between the front bow and the middle bow from the rear edge of the front bow over or under the middle bow so that the canvas folding top falls into a Z-fold. This orderly lowering of the canvas folding top is facilitated if, for example, the canvas folding top is attached to the middle bow since, then, the irregular lateral yield of the canvas folding top which may occur is reliably prevented. Furthermore, the moving over one another yields a compact arrangement of the front bow and middle bow which is short in the lengthwise direction of the vehicle and which is advantageous when the folding roof is lowered. 
     To facilitate the sequence of movements when the canvas folding top is being folded, it is advantageous if, during the backward displacement of the front bow which is moved by the drive on the guide means against the middle bow, the middle bow is fixed on the guide means by a lock means until the front bow is positioned in a defined manner on the middle bow with the formation of a Z-fold of the canvas folding top. This ensures that the middle bow cannot shift to the rear on the frame of the folding top when the front bow is pushed to the rear. 
     One practical embodiment of the invention calls for the front bow, in its defined arrangement on the middle bow, being coupled to the middle bow by a coupling means and the middle bow being fixed by the lock means being disengaged so that the driven front bow and the middle bow form a movable bow unit. Thus, by means of a drive which acts on the front bow, the entire bow unit can be pushed with the Z-folding being preserved. The displacement can be performed in both displacement directions, i.e., during opening and also closing of the canvas folding top and the folding roof. 
     The guide means for the two bows can have guide rail on each of the two side roof rods. The middle bow can be blocked by the lock means having a pre-tensioned lock rocker which is located on the bearing unit of the middle bow with a lock hook which fits into a recess on the guide rail for fixing the middle bow. 
     To cancel the blocking of the middle bow, it is advantageous if the lock rocker can be swung by the front bow, which is pushed onto the middle bow, and can be released from the fixing engagement. Then, the lock hook can be forcibly raised by the moving front bow in a single sequence of motion. The opposite motion sequence causes blocking of the middle bow when the front bow moves away from the middle bow. 
     In a preferred embodiment, the lock rocker, which swings in the respective direction, couples and uncouples the middle bow on the front bow. 
     If at least one other middle bow is movably supported on the guide means or the guide rails and can be fixed according to the first middle bow and can be moved as a unit with the front and middle bow after its fixation is released, proper folding of the canvas folding top be ensured even for longer folding roofs. In this way, different open positions of the folding roof with roof openings of different sizes can also be set. 
     For at least partial travel of the front bow over the middle bow, it is advantageous if each side guide rail has its own guideway for the sliding means of the front bow and for the sliding means of the middle bow, so that the sliding means can be moved next to one another. Thus, the sliding means can be located next to one another on the guide rail in a space-saving manner or can also be moved past one another when this is necessary for a compact arrangement. The sliding means can be made such that they have at least one sliding element which is movably held on the respective guideway. 
     The mechanism of the folding top is preferably made such that the side roof rod is pivotally connected by a pivot joint to a side part of the main bow, and that to lower the folding roof into the storage space, the roof rod is swung in, the pivoting, motion of the roof rod taking place, for example, in a roughly horizontal plane of the motor vehicle. Furthermore, the mechanism of the folding top can have a roof cassette which is formed from the side part and the main bow and which is pivotally supported on the body via a respective parallelogram-like four-bar arrangement which contains the main column and a main connecting rod. 
     The drive for the front bow can be located on the main bow, the roof cassette or the rear roof rod and is connected via cable pulls or Bowden cables to the front bow. 
     With the described mechanism of the folding top, a partial opening of the folding top for ventilation of the interior can be established by moving the front bow, the canvas folding top being placed into a Z-shaped fold which offers little air resistance and does not tend towards fluttering. Thus, this operation can be performed even while driving. 
     These and further objects, features and advantages of the present invention will become apparent from the following description when taken in connection with the accompanying drawings which, for purposes of illustration only, shows a single embodiment in accordance with the present invention. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view showing a portion of a folding top mechanism of a folding roof for a convertible; 
     FIG. 2 is a schematic side view a front bow and a middle bow on a guide of the folding top mechanism in a position with the middle bow locked; 
     FIG. 3 is a schematic side view corresponding to that of FIG. 2, in a position with the middle bow unlocked; 
     FIG. 4 is a side elevational view showing the front bow in its arrangement over the middle bow; 
     FIG. 5 is a schematic cross-sectional view of the guide of the folding top mechanism with the front bow and the middle bow supported thereon; 
     FIG. 6 is a partially exploded perspective view of the folding top mechanism of the folding roof; 
     FIG. 7 is a perspective overhead view of the folding top mechanism similar to that of FIG. 6, but with the front and middle bows moved over one another; and 
     FIG. 8 is a perspective view of the folding top mechanism similar to that shown in FIG. 6, but with the front and middle bows moved over one another into a rear position. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The mechanism of a folding top contains a side roof rod  1  (see FIG. 1 in which only the left half of the folding top mechanism is shown, the right being the mirror image thereof) with a guide rail  2 , on which the front bow  3  and the middle bow  4  are movably supported. On its back end  5 , the roof rod  1  is connected to a side part  6  of a roof cassette  7 . The roof cassette  7  contains a main bow  8  which forms a permanent connection between the left side part  6  and the corresponding opposite right side part. 
     The bearing unit  9  of the front bow  3  (see FIG. 2) contains a rest  11  which is supported on a sliding element  10  (see FIG. 5) on the guide rail  2  and on which a cross beam  12  of the front bow  3  is supported to be able to pivot on a pin  13 . The cross beam  12  is pre-tensioned by a spring  14  in the direction of a position which is inclined forward and downward. 
     The bearing unit  15  of the middle bow  4  contains a rest  17  which is supported by a sliding element  16  (see FIG. 5) on the guide rail  2  and to which the middle bow  4  is attached. A lock means for fixing the middle bow  4  on the guide rail  2  and for blocking it against displacement has a lock rocker  18  which is mounted to be able to pivot around the horizontal rocker axis  19  on the bearing unit  15 . The lock hook  20  of the lock rocker  18  is pre-tensioned by a spring of the lock rocker  18  against the guide rail  2  and is pressed into a recess  21  in the guide rail  2  in the lock engagement position, as shown in FIG. 2, so that the middle bow  4  is fixed on the guide rail  2  and is blocked against displacement along the guide rail  2 . 
     When the front bow  3  is pushed against the middle bow  4 , by a drive (not shown), for example via a conventional drive cable, a driving pin  22  which projects laterally from the rest  11  of the bearing unit  9  of the front bow  3  presses against a stop surface  23  on the lock rocker  18  which thereupon swings up and lifts the lock hook  20  out of the recess  21 , by which fixation of the middle bow  4  is canceled (see, FIG.  3 ). In doing so, the driving pin  22  is held in a recess  24  on the lock rocker  18 , thus establishing the coupling of the front bow  3  and the middle bow  4  and enabling displacement of the driven front bow  3  and the middle bow  4  as a unit in both directions of displacement along the guide rail  2 . 
     The guide rail  2 , which is attached to the roof rod  1 , contains two separate guideways  25  and  26  (see, FIG.  5 ). The guideway  25  is located on the top of the guide rail  2  and contains the sliding element  16  of the bearing unit  15  of the middle bow  4 . The guideway  26  is located on the inside of the guide rail  2  and contains the sliding element  10  of the bearing unit  9  of the front bow  3 . This separate accommodation of the sliding elements  10 ,  16  and the laterally spaced arrangement of the rests  11  and  17  of the two bearing units  9  and  1   5  make it possible for the sliding elements  10  and  16  to be pushed next to one another, and thus, also the front bow  3  to be pushed onto and over the middle bow  4  (see, FIG.  4 ). In this position, the front bow  3  is slightly inclined so that its rear edge  27  is raised above the middle bow  4 . When the folding top is closed, the canvas folding top (only a portion of which is schematically represented as noted below) presses the front bow  3  into a roughly horizontal alignment 
     The canvas folding top is attached to the front bow  3  and the middle bow  4 . When the front bow  3  is pushed relative to the middle bow  4  and the top part  28  of the front bow travels over the blocked middle bow  4  (see, FIG.  4 ), a Z-shaped fold in the unattached portion of the canvas folding top (schematically represented by a broken line in FIG. 4) necessarily forms between the front bow  3  and the middle bow  4 . 
     FIG. 6 shows important elements of the left half of the mechanism of the folding top (and in addition the right roof rod  1 ′) The guide rail  2  is attached inside to the roof rod  1  which has a profile seal  29  with the guideway  25  facing upward for the middle bow  4  and the guideway  26  facing inward for the front bow  3 , which in the front position adjoins a wind deflector or a top windshield cross member. 
     FIG. 7 shows the front bow  3  and the middle bow  4  in its coupled arrangement pushed into and on top of one another. This unit can be pushed farther back as far as onto the roof cassette  7  (see, FIG.  8 ), to the side part  6  of which a guide rail corresponding to the guide rail  2  is attached or integrated. The front bow  3  and the middle bow  4  largely or completely overlap the main bow  8  in this position, in turn, a Z-fold of the canvas folding top free between the middle bow  4  and the main bow  8  being formed analogously to the first Z-fold. 
     The roof rod  1  is attached, for example, to the side part  6  of the roof cassette  7  via a pivot joint and is pivoted inward roughly parallel to the main bow  8  into a cross position for folding back and lowering the folding roof in a space-saving manner. The roof cassette  7  is supported via a parallelogram-like four-bar arrangement  30  with a main column  31  and a main connecting rod  32  on the body and is swung into a storage space while retaining its roughly horizontal alignment when the drive pivots the main column  31  of the main connecting rod  32 . 
     Instead of the one middle bow  4 , at a corresponding length of the folding top or the folding top mechanism, there can also be two or more middle bows in succession, and in the described way, with the formation of additional Z-folds of the canvas folding top, they can be pushed into and on top of one another. To do this, also one or more guideways for the sliding elements of the additional middle bow can be made on the guide rail. But, the sliding elements can also be held by two bows in one guideway. With a corresponding configuration of the rest and the bearing unit the two bows can still be located in and on top of one another even if the sliding elements cannot be pushed past one another, but can only be pushed against one another. 
     The folding top is closed by swing up the folding top mechanism out of the lowered position in the storage space and by pivoting the roof rod  1  out. The front bow  3  is pushed forward and via the driving pin  22  entrains the middle bow  4  until it reaches its blocked position (FIGS. 2 &amp; 7) in which the lock hook  20  drops into the recess  21 . At the same time, the driving pin  22  is released from its coupled engagement on the lock rocker  18  so that the front bow  3 , which continues to be driven, can be pushed into its front closed position on the scoop. The canvas folding top is tensioned again. 
     While only a single embodiments in accordance with the present invention has been shown and described, it is understood that the invention is not limited thereto, and is susceptible to numerous changes and modifications as known to those skilled in the art. Therefore, this invention is not limited to the details shown and described herein, and includes all such changes and modifications as are encompassed by the scope of the appended claims.