Abstract:
The invention is based on a wiper blade ( 12 ) with a wiper strip ( 14 ) which has a wiper lip ( 16 ) and a head strip ( 20 ) which is integrally formed on said wiper lip and, in a first longitudinal channel ( 26 ), has a supporting element in the form of a spring rail ( 18 ) with a flat cross section, and has a spoiler ( 22, 38, 46 ) on that side which faces away from the wiper lip ( 16 ). It is proposed that the spoiler ( 22, 38, 46 )=surrounds the head strip ( 20 ) on its longitudinal sides by means of guide rails ( 40 ).

Description:
BACKGROUND OF THE INVENTION 
       [0001]    The invention relates to a wiper blade. 
         [0002]    DE 198 35 065 A1 discloses a joint-free wiper blade, the basic body of which consists essentially of a head strip, on which a wiper lip is integrally formed via a tilting web. The head strip possesses a longitudinal duct in which a spring-elastic carrying element is embedded. The latter has a rectangular cross section, the wide side running approximately parallel to the vehicle windshield. The width of the carrying element decreases from the middle region toward the ends. The carrying element, due to its curvature, persists during operation a prestress such that the wiper blade bears with its wiper lip against the vehicle windshield with suitable pressure force. That side of the head strip which faces away from the wiper lip is flat and possesses a uniform wall thickness with respect to the longitudinal duct. On the back of the head strip, in the middle region of the wiper blade, an adapter is attached which serves for connecting the wiper blade to a wiper arm and which laterally surrounds the head strip in the region of the carrying element by means of claws. 
         [0003]    A joint-free wiper blade with a head strip, on which a wiper lip is integrally formed in the conventional way, is known from DE 10 334 609 A1. The head strip has a longitudinal duct for receiving a spring-elastic carrying element having a cross section running in an elongate manner transversely with respect to the wiper lip. On the cover side of the head strip which faces away from the wiper lip, a spoiler is integrally formed. This may consist of the same material as the head strip or of a softer material. In both cases, the wiper blades are expediently produced by an extrusion method. 
         [0004]    Furthermore, DE 10 2005 009 205 A1 discloses a joint-free wiper blade with a wiper strip, the head strip of which has two lateral longitudinal grooves and of which the cover side, which faces away from a wiper lip, is connected to an elongate spring-elastic carrying element. The latter has a rectangular cross section in a direction transverse with respect to the head strip. The carrying element and part of the head strip are surrounded by a guide rail which engages with longitudinally running legs into the lateral longitudinal grooves of the head strip. The guide rail is itself guided in a guide profile of a spoiler, so that the spoiler is firmly connected to the wiper strip. 
       SUMMARY OF THE INVENTION 
       [0005]    According to the invention, the spoiler is designed as a separate component and with guide rails surrounds the head strip on its longitudinal sides. The spoiler can thereby be produced independently of the wiper strip from a material which, on the one hand, impedes the pressure force of the wiper blade only slightly and, on the other hand, allows good lateral guidance. In this case, it may be expedient that the guide rails are extruded on the spoiler and have a higher hardness than the remaining spoiler. 
         [0006]    In order to reduce the weight of the spoiler and improve its flexibility, it is advantageous that the spoiler possesses, on that side of the head strip which faces away from the wiper lip, at least one second longitudinal duct which runs parallel to the first longitudinal duct and which has a similar cross section to the first longitudinal duct. As a result, during the mounting of the wiper strip, the guide rails can be bent up elastically outward, so that the wiper strip does not have to be pushed in the longitudinal direction of the spoiler between the guide rails, but, instead, can be inserted transversally with respect to the spoiler between the guide rails. At least one end piece closed on the end face can thus be formed integrally on the spoiler, with the result that at least one of the otherwise conventional end caps of the wiper blade may be dispensed with. The second longitudinal duct may advantageously be connected via a longitudinal gap to the space between the guide rails for receiving the head strip. The longitudinal gap is conducive to bending up the guide rails, particularly when these consist of a harder material than the remaining spoiler. 
         [0007]    Moreover, the second longitudinal duct may receive a second spring rail which, together with the first spring rail, forms the carrying element. This affords further possibilities for modifying the overall spring rigidity of the carrying element, in that the cross section of one and/or of both spring rails varies in its width and/or height over the length of the spring rail. The spring properties of the spring rails can thereby be modified within wide limits, so that the pressure forces over the length of the wiper blade can be adapted optimally to the stipulations of the respective application. As a rule, the width and/or the height will increase from the ends of the spring rail toward its middle region. Basically, other characteristics may also be implemented, in which the width and/or the height increase or decrease in a wavy or stepped manner. 
         [0008]    The second spring rail, which runs parallel to the first spring rail in the spoiler, may be modified in its cross section in the same way as the first spring rail. Moreover, the two spring rails may possess different lengths, preferably the second spring rail being selected to be shorter than the first spring rail. After the mounting of the wiper strip, the second spring rail is pushed into the spoiler in the longitudinal direction. In the mounted state, said second spring rail stiffens the spoiler profile and blocks the guide rails, so that these can no longer be bent up laterally. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0009]    Further advantages may be gathered from the following drawing description. Exemplary embodiments of the invention are illustrated in the drawing. The drawing, description and claims contain numerous features in combination. A person skilled in the art will expediently also consider the features individually and combine them into appropriate further combinations. 
           [0010]    In the drawing: 
           [0011]      FIG. 1  shows a side view of a wiper blade according to the invention, 
           [0012]      FIG. 2  shows a perspective section along the line II-II in  FIG. 1 , 
           [0013]      FIG. 3  shows a variant of  FIG. 1 , 
           [0014]      FIG. 4  shows a perspective view of one end of the wiper blade as a variant of  FIG. 1 , 
           [0015]      FIG. 5  shows a perspective and partially transparent view of a wiper blade with a carrying element which has a variable cross section over its length, 
           [0016]      FIG. 6  shows a perspective and partially transparent view of a wiper blade with a first carrying element with which a second carrying element is arranged in a longitudinal duct of the spoiler, 
           [0017]      FIG. 7  shows a variant of  FIG. 6 , 
           [0018]      FIG. 8  shows a cross section through a spoiler with extruded-on guide rails for the wiper strip, and 
           [0019]      FIG. 9  shows a cross section through a spoiler according to  FIG. 8  with a mounted wiper strip having two carrying elements. 
       
    
    
     DETAILED DESCRIPTION 
       [0020]      FIG. 1  shows a non-loaded wiper blade  12  on a vehicle windshield  10 . It possesses a wiper strip  14  with a wiper lip  16  ( FIG. 2 ) which is connected in the conventional way to a head strip  20 . On that side of the head strip  20  which faces away from the wiper lip  16 , a spoiler  22  is provided, which laterally surrounds the head strip  20  by means of guide rails  30 . End caps  24  are placed at the ends of the wiper blade  12 . At least one of these may be dispensed with if it is replaced by an end piece which is integrally formed on the spoiler  22  and which is designated by  48  in the version according to  FIG. 4  in the case of a spoiler  46 . 
         [0021]    Located in the head strip  20  is a longitudinal duct  26  for receiving a first spring rail  18  which serves as a carrying element for the wiper blade  12 . The spring rail  18  is bent forward such that, in the non-loaded state ( FIG. 1 ), it imparts to the wiper blade  12  a curvature which is greater than the greatest curvature of the vehicle windshield  10 . A wiper arm, not illustrated, transmits to a connection element  56 , having a hub  60  and fastened to the wiper blade  12  by means of claws  58 , a pressure force which presses the wiper lip  16  of the wiper blade  12  onto the vehicle windshield  10 , the aim being to achieve over the length of the wiper lip  16  an optimal pressure distribution which influences the wiping quality. The pressure distribution depends, inter alia, on the curvature of the vehicle windshield  10  and on the carrying element in the form of the spring rail  18  and also on its spring properties. These are determined, on the one hand, by the material and, on the other hand, by the cross-sectional distribution of the spring rail  18  over the length. 
         [0022]    The spring rail  18  illustrated in  FIG. 5  possesses a width  50  and a height  52  which increase from the ends toward the middle region. This may take place continuously or in a stepped manner. Narrower regions may alternate with wider regions or flatter regions may alternate with higher regions. As a further possibility of a variation, there are modifications in which only the width  50  or the height  52  is varied or the variations are carried out in combination and are coordinated correspondingly with one another. 
         [0023]    In the version according to  FIG. 6 , the carrying element consists of two spring rails  18  and  28 , the first spring rail  18  being accommodated in the longitudinal duct  26  of the head strip  20 , while the second spring rail  28  is arranged in a longitudinal duct  32  of the spoiler  22 . The second spring rail  28 , which runs at a distance from and parallel to the first spring rail  18  on that side of the head strip  20  which faces away from the wiper lip  16 , may be modified in the same way as the first spring rail  18 . Furthermore, the spring rails  18 ,  28  may have different lengths, with the cross section remaining the same, or in addition to the other modifications. In the example illustrated, the second spring rail  28  is shorter than the first spring rail  18 . Basically, however, the first spring rail  18  may also be the shorter. As compared with the version according to  FIG. 6 , in the version according to  FIG. 7  the spring rails  18  and  34  possess an identical length, but their width  50  varies over their length. 
         [0024]    The material of the spoiler  22  may be selected such that the spoiler  22 , in conjunction with the longitudinal duct  32  and, if appropriate, with a further longitudinal duct  36 , is flexible such that its guide rails  30  can be elastically bent up laterally in order to mount the wiper strip  14 . The wiper strip  14  therefore does not have to be mounted in the longitudinal direction of the spoiler  22 , but, instead, can be inserted transversely thereto between the guide rails  30 . This operation may be made easier in that, as shown in the exemplary embodiment according to  FIG. 3 ,  FIG. 8  and  FIG. 9 , the longitudinal duct  42  in the spoiler  38  is connected via a longitudinal gap  44  to the interspace between the guide rails  40 . In this case, as depicted by dashed lines in  FIG. 8 , the spoiler  38  can easily be bent up in the direction of the arrow  54 . 
         [0025]    The longitudinal gap  44  is advantageous, above all, when the spoiler  38  consists of two materials, specifically of a harder material for the guide rails  40  and of a softer material for the remaining spoiler  38 . What is thereby achieved at the same time is that, along with a good lateral guidance of the wiper strip  14 , the spoiler  38  possesses a high flexibility in the longitudinal direction perpendicularly to the vehicle windshield  10 . 
         [0026]    To mount the wiper blade  12 , first, the first spring rail  18  is inserted into the longitudinal duct  26  of the head strip  20 . The head strip  20  is thereafter inserted into the bent-up profile of the spoiler  38 . To stiffen and block the guide rails  40 , finally, the second spring rail  34  is inserted into the longitudinal duct  42  of the spoiler  38 , so that the guide rails  40  can no longer be bent up laterally in the direction of the arrow  54  ( FIG. 9 ). The configuration possibilities according to the invention give rise to so many variation possibilities that all possible applications can be covered by the wiper blade  12 .