Abstract:
The invention relates to a wiper blade for wiping windows, in particular motor vehicle windows, comprising a support element ( 12 ) for accommodating a wiper strip ( 14 ), to which support element a connecting device ( 20 ) is fastened, which connecting device has a part ( 15 ) on the wiper blade side having projections ( 50, 52 ) that engage behind the support element ( 12 ) at least in some regions. The invention further relates to a method for producing such a wiper blade. According to the invention, at least one shim element ( 62, 64 ) is arranged between the support element ( 12 ) and the engagement of the projections ( 50, 52 ).

Description:
BACKGROUND OF THE INVENTION 
       [0001]    The invention relates to wiper blades for wiping windscreens, particularly vehicle windscreens, having a support element for receiving a wiper strip to which a connecting device is fastened, the connecting device having a part on the wiper blade side with projections which engage behind the support element at least in places. In such wiper blades, the support element should guarantee the most uniform distribution possible of the wiper blade contact pressure emanating from the wiper arm on the windscreen over the entire wiping area covered by the wiper blade. Through a corresponding curvature of the unloaded support element—in other words when the wiper blade does not rest against the windscreen—the ends of the wiper strip which are completely applied to the windscreen when the wiper blade is in operation are loaded to the windscreen by the then tensioned support element, even if the curvature radii of spherically curved vehicle windscreens change with each wiper blade position. The curvature of the wiper blade must therefore be slightly greater than the greatest curvature measured in the wiping area on the windscreen to be wiped. A connecting device is fastened to the support element, by means of which the connection to the wiper arm is made. 
         [0002]    EP 1564094 B1 discloses that the connecting device can be fastened to the support element by means of projections which extend through the support element and are flared on an opposite side. Since the alternating bends which occur in this area during the wiping operation are considerable, the projections are also subject to an extreme load. The projections cannot be enlarged arbitrarily, as this would require the openings required in the support element to be enlarged too, which would lead to a significant weakening of the support element in this highly sensitive region. 
       SUMMARY OF THE INVENTION 
       [0003]    The wiper blade according to the invention has the advantage that relative movements between the projections and the support element can be at least partially absorbed by the additional shim elements, which leads to a removal of the load from areas at risk of notching. The diameters of the projections and therefore those of the openings may be kept at a size determined mainly by the tensile stresses and less so by the shear stresses which occur. 
         [0004]    The measures according to the invention give rise to advantageous developments of the wiper blade. Hence, a favorable friction value occurs when the shim elements are made of the same material as the part of the connecting device on the wiper blade side, which part is usually made from a thermoplastic material. 
         [0005]    If the shim elements are integrally formed on the part of the connecting device on the wiper blade side in an articulated, non-detachable manner, the process reliability during production of the wiper blade increases. 
         [0006]    The movability, particularly the ability of the support element to bend relative to the projections, is increased by a convexly held side facing the support element. 
         [0007]    The freedom of the bending movement between the support element and the part on the wiper blade side with its projections is improved when the side of the part on the wiper blade side facing the support element exhibits convex areas in the region of the projections. On the one hand, these allow a certain distance between the support element and the side of the part on the wiper blade side facing the support element, which distance may be larger or smaller according to the curvature radius of the support element, depending on the wiping position on the windscreen. On the other hand, they allow a certain roll-off of the support element on the convex area. These convex areas may also be designed as separate shim elements and therefore be better adaptable to the working conditions. 
         [0008]    The method according to the invention for producing a wiper blade is characterized in that it offers a simple way of producing the wiper blades according to the invention. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0009]    In the drawing: 
           [0010]      FIG. 1  shows a wiper blade according to the invention in a perspective view with the wiper arm indicated using a dot-dash line and the surface of a windscreen indicated using a dot-dash line, 
           [0011]      FIG. 2  shows a view according to II-II in  FIG. 1 , 
           [0012]      FIG. 3  shows a schematic representation of the view according to  FIG. 2  with only one spring strip, 
           [0013]      FIG. 4  shows a schematic view in the viewing direction IV in  FIG. 1  with only one end cap and 
           [0014]      FIGS. 5 to 7  show embodiments in a sectional detail view in each case. 
       
    
    
     DETAILED DESCRIPTION 
       [0015]    A wiper blade  10  shown in  FIG. 1  has a resilient support element  12  elongated in a strip-like manner ( FIGS. 1 and 2 ), on the lower strip side  13  facing the windscreen whereof is fastened an elongated, rubber-elastic wiper strip  14  in a manner parallel to the longitudinal axis. On the upper strip side  11  facing away from the windscreen of the support element  12  also to be referred to as a spring strip, the part  15  on the wiper blade side of a connecting device  20  is arranged in the center portion of said support element, with the help of which connecting device the wiper blade  10  can be detachably connected to a wiper arm  16  depicted by a dot-dash line in  FIG. 1 . The wiper arm  16  driven in oscillating fashion in the direction of a double arrow  18  in  FIG. 1  is depicted in the direction of an arrow  24  to the windscreen to be wiped—loaded to the windscreen of a vehicle, for example—the surface of which is depicted in  FIG. 1  by a dot-dash line  22 . Since the line  22  is intended to represent the greatest curvature of the windscreen surface, it should be clearly evident that the curvature of the as yet unloaded wiper blade with its two ends resting against the windscreen is greater than the maximum windscreen curvature ( FIG. 1 ). Under the contact pressure (arrow  24 ), the wiper blade  10  with its wiper lip  26  is applied to the windscreen surface  22  over its entire length. Tension develops as a result in the resilient support element  12  which is usually made of metal, said tension ensuring a proper bearing of the wiper strip  14  or of the wiper lip  26  against the windscreen surface  22  over its entire length and also a uniform distribution of the contact pressure (arrow  24 ). 
         [0016]    The particular embodiment of the wiper blade according to the invention will be described in greater detail below. 
         [0017]    It can be seen in  FIG. 2  that the support element  12  is made up of two spring strips  28  and  30  separated from one another, which are spaced apart from one another and create a gap  32 . The part  15  of the connecting device  20  on the wiper blade side exhibits two receiving means  34  and  36  in a lower region, in which the spring strips  28  and  30  each rest laterally. The receiving means  34  and  36  therefore rest against the sides of the spring strips  28  and  30 , while the part of the connecting device  20  corresponding to the wiper arm  16  is arranged on the convex side  29  of the support element  12  and the concave side  31  lies opposite this. 
         [0018]    The part  15  of the connecting device  20  on the wiper blade side is represented schematically in  FIG. 3 , wherein the corresponding spring strip  28  is drawn in the receiving means  34 , while the spring strip  30  does not lie in the corresponding receiving means  36 . In the region above the spring strips  28  and  30  and also above the gap  32 , the part  15  exhibits a recess  40  into which a top part of a wiper strip comes to lie when the wiper blade  10  is assembled. Projections  50  and  52  are arranged in the region between the receiving means  34  and  36 , said projections extending parallel to the receiving means  34  and  36  in the direction of the spring strips  28  and  30  to be received starting from the part  15 . The supporting element  12  or the spring strips  28  and  30  thereof are therefore equipped with openings  54  and  56  to receive the projections  50  and  52 . 
         [0019]    The outer end of the projections  50  and  52  is formed into a head  58  and  60 , respectively, in each case ( FIG. 2 ). A shim element  62 ,  64  is inserted between each head  58 ,  60  and the respective spring strip  28 ,  30 . 
         [0020]    The wiper blade  10  depicted from below in  FIG. 4 , which is drawn without the wiper strip  14  or wiper lip  26 , shows the spring strips  28  and  30 , the gap  32  and also the receiving means  34  and  36  of the part  15  of the connecting device  15  on the wiper blade side. It is evident that in this embodiment of the wiper blade  10  the spring strips  28  and  30  are completely separate from one another and only held together by the part  15  of the connecting device  20  on the wiper blade side or via end caps  38 , only one of which is depicted on an end in  FIG. 4 . The lower ends of the projections  50  and  52  are furthermore depicted projecting through the spring strips  28  and  30 . As already evident in  FIG. 2 , the projections  50  and  52  each exhibit an enlarged head  58  and  60 , via which the spring strips  28  and  30  are connected to the part  15  in a form-fitted manner. The heads  58  and  60  are usually produced by supplying heat to the outer ends of the projections  50  and  52 . 
         [0021]    Between the heads  58  and  60  and the spring strips  28  and  30 , the shim elements  62  and  64  can be identified as an outer ring. In this exemplary embodiment, the shim elements  62 ,  64  are of annular design similar to a shim element. They are made of the same material as the projections  50 ,  52  in this case and therefore as the part  15  of the connecting device  20  on the wiper blade side. 
         [0022]    In the following embodiments the same parts are each referred to using the same reference numbers. 
         [0023]    In  FIG. 5  an embodiment of the wiper blade  10  according to the invention is presented in the partial images  a  and  b , wherein  5   a  corresponds to the presentation according to  FIGS. 2 and 5   b  is a partially broken out side representation. The shim elements  62 ,  64  not only overlap the projections  50 ,  52  but also part of the receiving means  34 ,  36 , which are cut out correspondingly for this purpose. 
         [0024]    Individual steps for producing the connection between the part  15  on the wiper blade side and the spring strips  28 ,  30  of the support element  12  are represented in  FIGS. 5   c  to  g . In  5   c , the part  15  on the wiper blade side is presented with its projections  58 ,  60  pointing upwards. The spring strips  28 ,  30  are put over these projections  58 ,  60 , so that they receive the projections  58 ,  60  in their openings  54 ,  56  ( FIG. 5   d ). 
         [0025]    The shim elements  62 ,  64  are put over the projections  54 ,  56  in  FIG. 5   e , wherein in this exemplary embodiment the shim elements  62 ,  64  have additional openings to receive parts of the receiving means  34 ,  36 . This helps to stabilize the connection. 
         [0026]    It can be seen in  FIG. 5   f  that the structure preassembled in this manner is worked by means of ultrasound sonotrodes  70 . It is evident from  FIG. 5   g  that by means of the sonotrodes  70  the heads  58  and  60  were integrally formed on the projections  52  and  60 . 
         [0027]    In further process steps no longer illustrated, the wiper strip  14  can now be inserted, the end caps  38  fitted and the connecting device completed where appropriate. 
         [0028]    A further embodiment of the wiper blade  10  according to the invention is depicted in the partial images  a  and  b  in  FIG. 6 , wherein  6   a  corresponds to the depiction according to  FIGS. 2 and 6   b  is a side view. The shim elements  62 ,  64  are connected to the receiving means  34 ,  36  by means of integral hinge joints  66 ,  68  in a substance-bonded manner. 
         [0029]    Individual steps for producing the connection between the part  15  on the wiper blade side and the spring strips  28 ,  30  of the support element  12  are depicted in  FIGS. 6   c  to  g . In  6   c  the part  15  on the wiper blade side with its projections  58 ,  60  is shown pointing upwards. In addition, the shim elements  62 ,  64  are integrally formed on the outer ends of the receiving means  34 ,  36  via integral hinge joints  66 ,  68 . The spring strips  28 ,  30  are put over the projections  58 ,  60 , so that they receive the projections  58 ,  60  in their openings  54 ,  56  ( FIG. 6   d ). 
         [0030]    In  FIG. 6   e  the shim elements  62 ,  64  are now folded over the projections  54 ,  56 , wherein in this exemplary embodiment the shim elements  62 ,  64  rotate about the integral hinge joint  66 ,  68 . The shim elements  62 ,  64  are thereby fastened to the part  15  on the wiper blade side non-detachably and therefore in a safe-mounting manner. 
         [0031]    It can be seen in  FIG. 6   f  that the structure preassembled in this manner is processed by means of ultrasound sonotrodes  70 . It can be seen in  FIG. 6   g  that the heads  58  and  60  have been integrally formed on the projections  52  and  60  by means of the sonotrodes  70 . 
         [0032]    In further process steps no longer depicted, the wiper strip  14  can now be inserted, the end caps  38  fitted and the connecting device completed where appropriate. 
         [0033]    As shown in  FIG. 7 , in a further embodiment the surface  72  facing the spring strip  28 ,  30  may be convex in design. This improves mobility between the projection  52 ,  54  and the spring strip  28 ,  30  and reduces the notch effect in this region without having a detrimental effect on strength or dimensional accuracy. 
         [0034]    Irrespective of this, the side facing the support element  12  of the part  15  on the wiper blade side may have a convex area  74  in the region of the projections  50 ,  52 , by means of which a roll-off of the spring strips  28 ,  30  relative to the part  15  on the wiper blade side is possible. This area means that a space is created between the spring strip  28 ,  30  and the side  76  of the part  15  on the wiper blade side facing the spring strip, said space creating the clearance required to change the curvature of the spring strip  28 ,  30 . The way in which the spring strip  30 ′ with the adapted curvature path is positioned is depicted in an exaggerated manner with a dot-dash line in  FIG. 7 . 
         [0035]    The convex area  74  may be configured independently of the shim elements  52 ,  54 . It is also possible for the convex region  74  not to be integrally formed on the part  15  on the wiper blade side but configured as a separate shim, which is indicated by the line  76  in  FIG. 7 . In this way, the notch effect can be reduced, as already mentioned. 
         [0036]    In the exemplary embodiments the shim elements are depicted as individual parts, wherein a shim element is assigned to each projection. It is also possible, however, for the shim elements to be designed such that they exhibit a plurality of openings for a plurality of projections. In addition, it is conceivable for only two or also more than four projections to be provided. Furthermore, it is possible for the shim elements to be provided from another material, for example from a metal, a glass fiber-reinforced plastic or the like. The spring strips may also be made of homogeneous or coated plastic or the like. It also lies within the framework of the invention for shim elements or convex areas to be provided on all projections or only on selected ones.