Abstract:
A wiper blade for motor vehicle windows has an elongated spring-elastic support element, an elongated, rubber elastic wiper strip which is pressable against a window to be wiped and is held substantially parallel to a longitudinal axis by the elongated, spring-elastic support element, a connection device for a driven wiper arm, the connection device being loaded toward the window and secured to a middle portion of the spring-elastic support element, remote from the window, the connection device being formed as a component which is separate from the support element, and a welding connection which connects the connection device with the support element, the support element being band-shaped, the connection device having a base resting flatly on a side remote from the window of the band-shaped support element and connected to the band-shaped supporting element by the welding connection.

Description:
CROSS REFERENCE TO A RELATED APPLICATION 
     This application is a continuation-in-part of U.S. patent application Ser. No. 09/202,652 filed Dec. 18, 1998, which has been allowed as U.S. Pat. No. 6,192,546. 
    
    
     BACKGROUND OF THE INVENTION 
     In wiper blades, the support element for the entire field swept by the wiper blade is intended to assure the most uniform possible distribution of the wiper blade contact pressure, originating in the wiper arm, against the window. By means of a suitable curvature of the unloaded support element—that is, when the wiper blade is not resting on the window—the ends of the wiper strip, which in wiper blade operation is pressed completely against the window, are located by the then tensed support element toward the window, even if the radii of curvature of spherically curved vehicle windows change in every wiper blade position. That is, the curvature of the wiper blade must be somewhat greater than the greatest curvature measured in the wiping field of the window to be wiped. the support element thus replaces the complicated support bracket construction with two spring rails disposed in the wiper strip of the kind used in conventional wiper blades. 
     In a known wiper blade of this type (German Patent Disclosure DE 26 14 457), the connection device is integrally joined to the support element. This may possibly be of secondary importance as long as the support element is made from a plastic which is therefore made by filling a suitable mold. However, if the support element is to be made of metal, then two demands directly contract one another. On the one hand, the support element should have good spring properties, but on the other the attachments of the connection device should be easily bent by approximately 90° out of the plane of the support element and fixed in that position, so that the loads occurring in operation between the wiper blade and the wiper arm can be absorbed on stop faces of these attachments. These two demands are virtually impossible to meet unless disadvantageous compromises in the choice of material are made. 
     In another known wiper blade (German Patent Disclosure DE 12 47 161), the support element is provided with a connection device as a separate component. This connection device is solidly joined to the support element with the aid of rivets. The requisite bores in the support element, however, lead to an undesired, because uncontrollable, change in the support element tension, so that a satisfactory window wiping result cannot be attained. 
     SUMMARY OF THE INVENTION 
     Accordingly, it is an object of present invention to provide a wiper blade for motor vehicle windows, which is a further improvement of the existing wiper blades. 
     In keeping with these objects and with others which will become apparent hereinafter, one feature of present invention resides, briefly stated, in a wiper blade, in which a connection device for a driven wiper arm has a base which rests flatly on a side remote from the window of a band-shaped support element, and is connected to the band-shaped support element by a welding connection. 
     In the inventive wiper blade, a choice of materials that suits the demands made of the particular component can be made for both the support element and the connection device. The joining of the two components to one another is done easily and economically by means of a welded connection. Further assembly steps can be omitted. Tests have shown that a welded connection does not impair, or insignificantly impairs, the contact pressure distribution by the support element and thus the outcome of window wiping. 
     If the support element and the connection device of the wiper blade are of metal, it can be expedient if the welded connection is a resistance weld. 
     Particularly in a wiper blade in which both the support element and the connection device are made of a plastic, operationally reliable and economical fastening of the connection device to the support element can be attained by means of ultrasonic welding. 
     The welding itself, both in resistance welding and ultrasonic welding, can be embodied as preferably multiple spot welds. 
     In a wiper blade of which major demands are made in terms of the load, however, the welded connection can also be embodied by a plurality of linear welds; with a view to the specifications to be met in terms of pressure distribution, the welds may extend either crosswise to the longitudinal direction or longitudinally of the band like support element. 
     A connection device that can be adapted without difficulty in view of the wiper arm design is obtained if it rests flatly with the base on the side of the bandlike support element remote from the window. 
     Especially good lateral guidance and holding of the two components to be joined together is attained if the protrusions are embodied as strips, which extend longitudinally of the support element. 
     A further-improved, stable holding of the connection device to the support element is attained if on the free ends of the strips, clawlike attachments oriented counter to one another are disposed, and the spacing between the clawlike attachments and the outside, remote from the legs of the base of the U is adapted to the thickness of the support element. 
     For positioning the connection device on the support element in the longitudinal direction thereof, the connection device can have at least one shoulder, pointing longitudinally of the support element, with which shoulder a counterpart shoulder of the support element is associated. The result is accordingly a positive positioning aid that becomes operative before the welding operation. 
     Absolute securing of the mounted position of the connection device on the support element is obtained if the connection device has at least two shoulders, pointing in opposite directions, with each of which the counterpart shoulder of the support element is associated. 
     Expediently, the shoulders of the connection device are embodied on a protrusion of the connection device, and the counterpart shoulders and are embodied on a recess, associated with the protrusion of the support element. 
     Further advantages features and refinements of the invention are described in the ensuing description of embodiments shown in the drawing. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a side view of a wiper blade according to the invention; 
     FIG. 2 is a plan view on the wiper blade of FIG. 1; 
     FIG. 3 is a view from below, on a larger scale of a support element that is part of the wiper blade and is provided with a first embodiment of the connection device; 
     FIG. 4 is a section taken along the line IV—IV through the arrangement of FIG. 3; 
     FIG. 5 is a view from below, on a larger scale, of a support element that is part of the wiper blade and is provided with a second embodiment of the connection device; 
     FIG. 6 is a section taken along the line VI—VI through the arrangement of FIG. 5; 
     FIG. 7 is a view from below, on a larger scale, of a support element that is part of the wiper blade and is provided with a third embodiment of the connection device; and 
     FIG. 8, a section taken along the line VIII—VIII through the arrangement of FIG.  7 . 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     A wiper blade  10  shown in FIGS. 1 and 2 has an elongated, spring-elastic support element  12 , to the underside of which an elongated, rubber-elastic wiper strip  14  is secured parallel to the longitudinal axis. A connection device  16 , with the aid of which the wiper blade can be detachably joined to a driven wiper arm  18 , is disposed on the support element, which can also be called a spring rail, in the middle portion thereof. A hook acting as a counterpart connection means is formed on the free end  20  of the wiper arm  18  and clasps a pivot pin  22  that belongs to the connection device  16  of the wiper blade. The securing between the wiper arm  18  and the wiper blade  10  is performed by securing means known per se and not shown in further detail, which are embodied as an adapter. 
     The wiper arm  18  and thus also the hook on its end  20  are loaded in the direction of the arrow  24  toward the window to be wiped, whose surface to be wiped is represented in FIG. 1 by a dot-dashed line  26 . Since the dot-dashed line  26  is intended to represent the greatest curvature of the window surface, it is clearly apparent that the curvature of the wiper blade, resting with both its ends on the window, is greater than the maximum window curvature. The wiper blade presses with the contact pressure (arrow  24 ) presses over its entire length with its wiper lip  28  against the window surface  26 . In the process, a tensing builds up in the spring-elastic support element  12  that assures proper contact of the wiper strip  14 , or its wiper lip  28 , over its entire length on the window. The connection between the support element  12  and the connection device  16  will now be explained in further detail in terms of FIGS. 3 and 4;  5  and  6 ; and  7  and  8 . 
     In the first embodiment of the invention, shown in FIGS. 3 and 4, the connection device  16  is pressed flatly, with the outside of its base  30 , against the surface, remote from the window to be wiped, of the bandlike support element  12 . The legs  32  and  34  of the U of the connection device  16  extend on the side of the base  30  of the U remote from the support element  12 . The pivot pin  22  is supported in the legs  32  and  34  of the U. The fastening of the connection device  16  to the support element  12  is done with the aid of a welded connection which will be described in further detail hereinafter. 
     While in the drawings the connection device  16  is substantially U-shaped cross-section, this is not necessary for the present invention. The connection device  16  must have only the base  30  or a base-like part, which can be flatly placed on the support element  12  and connected with the latter. 
     As a positioning aid, the base  30  of the connection device has a protrusion  38 , extending from the side remote from the legs  32  and  34  of the U, and this protrusion has two shoulders  40  and  42  pointing in opposite directions—in the longitudinal direction of the support element  12 . These shoulders  40  and  42  are each assigned a respective counterpart shoulder  44  and  46  of the support element, and the counterpart shoulders are embodied at a recess  48  of the support element  12 . Because these shoulders point in the longitudinal direction of the support element, a positive connection is obtained between the support element  12  and the connection device  16  longitudinally of the support element. This positive engagement acts as a positioning aid when the welded connection is to be made. 
     In the exemplary embodiment of FIGS. 5 and 6, which shows a refinement of the arrangement of FIGS. 3 and 4, two striplike protrusions  60  and  62  are disposed, spaced apart from one another by a distance adapted to the width  64  of the support element  12 , on the side of the base  30  of the U remote from the legs  32  and  34  of the U. The striplike protrusions  60  and  62  extending longitudinally of the support element  12  from lateral guides, which secure the position of the connection device  16  on the support element  12  crosswise to its longitudinal extent. 
     The embodiment of FIGS. 7 and 8 is based on the embodiment of FIGS. 5 and 6. In a departure from that embodiment, for further simplification of preassembly, the striplike protrusions  160  and  162  are provided, on their free ends remote from the base  30  of the U, with clawlike attachments  166  and  168  pointing in opposite directions from one another. The spacing between the outside of the base  30  of the U, remote from the legs  32 ,  34  of the U, and the side oriented toward the base of the attachments  166  and  168  is adapted to the thickness  170  of the support element  12 . This adaptation is made such that just as in the embodiment of FIGS. 5 and 6, an easy but largely play-free relative motion between the two components  12  and  16  is possible. 
     It is shown in the embodiment of FIGS. 3 and 4 that the welded connectoin comprises a plurality of spotlike welds  36 . In the embodiment of FIGS. 5 and 6, the welded connection has a plurality of linear welds  136 , whose longitudinal extent is crosswise to the longitudinal direction of the support element  12 . In the embodiment shown in FIGS. 7 and 8, the welds  236  are also linear. In a departure from the arrangement in FIGS. 5 and 6, in this embodiment of the invention the linear welds  236  are in the longitudinal direction of the support element  12 . 
     The connection device  16  can be welded to the support element in one point or in one strip in a first region, and claws can be provided in which the connection device is additionally fixed to the support element, similarly to the claws shown in FIG.  8 . With such a construction, the support element can make, while wiping the windshield having a changing curvature, a movement relative to the connection device which is perpendicular to the windshield. As a result, there is no tension between the connection device and the support element during the wiping movement. 
     In practice, it has been found that the few welds  36  or  136  or  236  assure an operationally safe and secure connection between the support element  12  and the connection device  116 . Any impairment to the spring properties of the support element is kept within such narrow limits that in view of the wiping results to be sought it can be practically ignored. It does not matter whether the spring element  12  and the connection device  16  are each of metal or are of plastic. It is illuminating that in this case even different kinds of plastics can be joined together, which in view of their properties meet the demands made of them. In the case of a metal version, a resistance weld can be expedient, while in a plastic version an ultrasonic weld can have advantages. 
     It should also be noted that the positive connection described in the embodiment of FIGS.  3  and  4 —that is, the protrusion  38  with its shoulders  40  and  42  and the recess  48  with its counterpart shoulders  44  and  46 —can also be used in the embodiments of FIGS. 5 and 6 and FIGS. 7 and 8. It is also worth noting that the bandlike support element  12  in the exemplary embodiments is indeed made in one part, but it can also comprise multiple parts without thereby departing from the scope of the present invention. 
     Nor need the arrangement of welds  36 ,  136  and  236  be absolutely selected as shown in FIGS. 3,  5  and  7 . On the contrary, it is also conceivable for them ti be disposed on the protrusions  60 ,  62 , and  160 ,  162 , or on the attachments  166 ,  168 . 
     It should also be pointed out that the shape of the welds  36  or  136  or  236  is independent of how the connection device  16  is embodied. The disposition and shaping of the welds are merely shown as an example in FIGS. 3,  5  and  7 . 
     It is clear that—in a departure from the exemplary embodiment shown—the counterpart shoulders  44 ,  46  need not necessarily be embodied on a recess, open at the edge, of the support element. In view of the operating tension present in the support element  12  and oriented toward the window  26 , it may be advantageous to dispose the counterpart shoulders in a region of the support element  12  that is invulnerable in this respect. this can be done for instance in the region of the support element  12  facing the central region of the base of the U. In that case, the counterpart shoulders are embodied on an opening that is closed all the way around. Accordingly, the shoulders cooperating with them should then be placed on the connection device. 
     It should also be remembered that the arrangement of the positioning aid described can be employed independently of whatever way in which the connection device is to be joined to the support element.