Patent Abstract:
The invention relates to a windshield wiper ( 10 ) for wiping windows, in particular of motor vehicles, having a connection piece ( 14 ) which can be connected to a wiper arm ( 12 ) and which is connected to a flat bar ( 16 ), and having a wiper strip ( 18 ) which is connected to the flat bar ( 16 ) and can be pressed against the window to be wiped. It proposed that the flat bar ( 16 ) has at least one joint ( 20, 26, 28 ), whose pivot axis ( 21 ) is oriented transversely to the longitudinal extent of the flat bar ( 16 ) and in the direction of its width.

Full Description:
BACKGROUND OF THE INVENTION 
     The invention relates generally to a windshield wiper having a connection piece which can be connected to a wiper arm and which is connected to a flat bar, and which has a wiper strip which is connected to the flat bar and can be pressed against the window to be wiped. Such windshield wipers are known for instance from European Patent EP 0 528 643, and they are distinguished over conventional wiper blades in that instead of a complicated support bracket frame, the contact pressure exerted by the wiper arm is transmitted to the wiper strip via a so-called flat bar. The flat bar as a rule comprises a pre-curved spring steel or a plastic rod. The wiper strip is glued to the flat bar, or it is received by the flat bar in the recesses intended for it. 
     For windshield wipers that have support bracket frames, it is known from German Patent Disclosure DE-OS 26 15 292 to form the support bracket of a wiper blade from two bracket parts, which have recesses and protrusions graduated in shoulderlike fashion. In the assembled position, the protrusions engage the recesses and are rotatably connected to one another via a pivot bolt that penetrates the protrusions. By way of the joint thus formed, the bracket parts can be pivoted relative to one another. In this way, an easily installed support bracket frame for a wiper blade is obtained. 
     ADVANTAGES OF THE INVENTION 
     The windshield wiper of the present invention has the advantage that because of the joint placed in the flat bar, the windshield wiper can be adapted exactly to even an extreme window curvature. The flat bar which is curved in the unloaded state must have a course of curvature in the unloaded position that is maintained precisely during wiping operation for a predetermined contact pressure distribution. By splitting that flat bar into at least two pieces, the part size that has to be machined and, thus, tool costs are less, and conversely the part tolerances to be expected are easier to adhere to. 
     From an assembly standpoint, it is especially simple if the joint is disposed in the region of the connection piece. The connection piece can then in turn take on a guide, stop and retention function. If one or more joints are disposed outside the region of the connection piece, then the flat bar can be adapted even more precisely to the curved course of the window to be wiped. 
     The contact pressure distribution which is definitively responsible for the wiping quality can be optimally set if the pieces, which are spring-connected to the joint or joints, are spring-loaded relative to one another. The joints can then be pressed in prestressed fashion against the surface of the window to be wiped. The prestressing can be composed of the intrinsic elasticity of the spring bar pieces on the one hand and of the spring-mounted joints on the other. 
     An especially simple stop to prevent excessive bending backward of the joint or joints is achieved if the two flat bar pieces that form the joint each have at least one extension that protrudes past the respectively other piece. The extensions are then braced on the respectively other pieces and prevent the flat bar from being hinged away from the window. The spring support of the joints can be achieved especially simply by placing an elastic element between each piece and the extension that protrudes past the piece. The elastic element is formed in the simplest case by the rubber of the wiper strip. In this way, an extremely economical flat bar wiper blade is made available that by way of the prestressing and the choice of spring furnishes an optimal distribution of contact pressure. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Exemplary embodiments of the windshield wiper of the invention are shown in the drawing and described in further detail below. Shown are FIG. 1, a windshield wiper connected to a wiper arm, seen from the side, in a first exemplary embodiment; 
     FIG. 2, a detail indicated by line II in FIG. 1 in an exploded view; 
     FIG. 3, a view similar to FIG. 2 in the assembled position, for a second exemplary embodiment; 
     FIG. 4, a detail along line IV in FIG. 1; and 
     FIG. 5, the detail of FIG. 4, taken apart. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     In FIG. 1, a windshield wiper  10  is shown that can be driven by a wiper arm  12 . The wiper arm  12  engages a connection piece  14  of the windshield wiper  10 , which in turn is connected to a flat bar  16 , which is represented merely as a line in FIG.  1 . On the side of the flat bar  16  opposite the connection piece  14 , there is a wiper strip  18 , which can be pressed against a windshield, not shown, of a motor vehicle. In the exemplary embodiment, the wiper strip  18  is glued on, but it can also be vulcanized on or clipped into recesses of the flat bar  16 . It is also possible for one or two flat bars  16  to be placed in recesses of the wiper strip  18 . 
     In the region of the connection piece  14 , the flat bar  16  has a first joint  20 , which separates the flat bar  16  into at least one first piece  22  and one second piece  24 . A second joint  26  and a third joint  28 , which subdivide the first and second pieces  22  and  24  into further pieces, respectively, are also disposed outside the connection piece  14 , in the region of the first piece  22  and the second piece  24 , respectively. The pivot axis  21  (FIG. 2) of the joint  20  is oriented transversely to the length of the flat bar  16  and in the direction of its width. 
     In FIG. 2, the first joint  20  is shown in an exploded view. The two pieces  22  and  24  each have one shoulder  30  in the region of the joint  20 , and with this shoulder they overlap one another in the assembled position. The shoulders  30  are pierced by a bore  32 , and in the installed state these bores are aligned with one another and receive a pivot bolt (not shown). The connection piece  14  rests on the flat bar  16  on the side opposite the wiper strip  18  and, with a sheet- metal tab  36  that has a bore  34 , it fits over the pivot region. The bore  34  is aligned with the bore  32  and in the assembled state is also pierced by the bolt, not shown. 
     The connection piece  14 , because of its length in the longitudinal direction of the windshield wiper, forms a stop that prevents the two pieces  22  and  24  from pivoting in the direction away from the between the window. 
     It is shown in suggested form in FIG. 2 that the connection piece  14  can have further sheet-metal tabs  37 , which clasp the spring bar  16  and form a stop in the other direction. Stops are not absolutely necessary, however, because the wiper strip  18  secured to the flat bar  16  presents a restoring force that counters overly sharp kinking of the joint  20 . 
     In FIG. 3, a further exemplary embodiment is shown, in which identical elements are provided with the same reference numerals. A wedgelike elastic means in the form of a rubber pad  38  is placed between the connection piece  14  and the pieces  22  and  24 , respectively, of the flat bar  16 , and these pads force the pieces  22  out of the plane into a slightly kinked position. The amount of deflection out of the plane is determined by the size of the rubber pad and by its spring constant in proportion to the spring constant of the wiper strip that counteracts this kinked setting. 
     In the exemplary embodiment of FIG. 3, the rubber pad  38  is a separate part, which is secured to the connection piece  14  with an attachment piece  40  that has a collar. To that end, the connection piece  14  has a recess, which receives the attachment piece  40  and is clasped by the collar of the attachment piece  40 . 
     In FIGS. 4 and 5, the second joint  26  is shown, which divides the first piece  22  into two subsidiary pieces  42  and  44  in turn and pivotably connects them to one another. To that end, the subsidiary pieces  42  and  44  have a shoulder  46 , analogous to the shoulder  30 , and are also pierced by an aligned bore, which in turn receives a pivot bolt  48 . In the assembled position, the bolt axis is coaxial to the pivot axis  21 . 
     For stop limitation and for the sake of better lateral guidance, the pieces  42  and  44  each have a respective extension  50 , which extends from the shoulder  46  in the direction of the respectively other piece  42  and  44 . The extension  50  is disposed above the flat bar  16 , on the side opposite the wiper strip  18 , and in the assembled position thus rests, in the manner of a stop limitation, on the respectively other piece  42  and  44 . 
     It is also possible in principle to provide only one extension  50  per joint. 
     An elastic element in the form of a rubber pad  52  is placed between the extension  50  and the respective piece  42  and  44  over which the extension  50  fits. This rubber pad  52  is wedge-shaped and forces the two pieces  42  and  44  into a kinked position oriented toward the window curvature. Analogously to the first joint  20 , here again the geometric variables of the rubber pad and the spring constants of the rubber pad  52  and of the wiper strip  18  predetermine the kinked position of the unloaded wiper blade. The rubber pad  52  is shown here as a separate part, but it can also be part of the wiper strip  52  and can extend from the wiper strip through recesses in the flat bar  16  into the pivot region. The rubber pad  52  could thus also take on a retention function of the wiper strip  18  relative to the flat bar  16 . 
     In the loaded state, that is, when the windshield wiper  10  is pressed against the window to be wiped, the contact pressure exerted by the wiper arm  12  is transmitted via the connection piece  14  to the flat bar  16  and in turn by it to the wiper strip  18 . The geometric cross-sectional shape, the curvature of the unloaded wiper blade, and the material constants of the wiper strip  18  and the spring bar have an influence on the distribution of contact pressure of the wiper strip  18  on the window. By means of the joints  22 ,  26 ,  28  and their rubber pads  38 ,  52 , the contact pressure distribution can furthermore be varied independently of the specifications of the flat bar  16 . To make it possible to follow even extreme window curvature courses exactly, it can be advantageous if a plurality of joints are distributed over the flat bar  16 . It is not absolutely necessary for the joints to be disposed symmetrically with respect to the longitudinal extent of the flat bar  16 . 
     It is also conceivable, instead of the extensions  50 , to provide a stop part which simulates the connection piece—and which does not contain the requisite lateral cheeks for retaining the wiper arm, nor the pivot bolt. This connection piece would then be placed analogously on the side opposite the wiper strip  18  and fixed via the pivot bolt. A stop limitation can be effected then by way of clawlike extensions  38 . 
     If the flat bar  16  rests in a recess that pierces the wiper strip  18  lengthwise or in lateral longitudinal grooves of the wiper strip  18 , then the rubber pads  38 ,  52  may be omitted. The extensions  50  can also be dispensed with under some circumstances. 
     It will be understood that each of the elements described above, or two or more together, may also find a useful application in other types of constructions differing from the types described above. 
     While the invention has been illustrated and described as a windshield wiper for an automobile, it is not intended to be limited to the details shown, since various modifications and structural changes may be made without departing in any way from the spirit of the present invention. 
     Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can, by applying current knowledge, readily adapt it for various applications without omitting features that, from the standpoint of prior art, fairly constitute essential characteristics of the generic or specific aspects of this invention. 
     What is claimed as new and desired to be protected by letters patent is set forth in the appended claims.

Technology Classification (CPC): 1