Patent Abstract:
A windshield wiper device ( 10 ), particularly for a motor vehicle, is proposed. This windshield wiper device comprises a wiper bearing ( 14 ) supporting a wiper shaft ( 16 ), which has an undercut ( 48 ) in which a securing device ( 40 ) for axially fixing the wiper shaft ( 16 ) in the wiper bearing ( 14 ) is arranged. The securing device ( 40 ) can be displaced by the effects of a defined axial force component (F) on the wiper shaft ( 16 ), whereby the wiper shaft ( 16 ) can be displaced in relationship to the wiper bearing ( 14 ). According to the invention, the securing device ( 40 ) comprises a bushing section ( 42 ) with an indentation ( 50 ), which engages in the undercut ( 48 ) of the wiper shaft ( 16 ).

Full Description:
BACKGROUND OF THE INVENTION 
     The invention relates to a windshield wiper device, particularly for a motor vehicle. 
     Numerous windshield wiper devices for motor vehicles having a wiper bearing supporting a wiper shaft, which can be displaced in relation to the wiper bearing by the effects of an axial force component, are known. 
     For example, a windshield wiper device is known from DE-A-198 51 816 in which the wiper shaft has a radial undercut, in which a securing device sits for axially fixing the wiper shaft in the wiper bearing. This securing device can be displaced by the effects of a defined axial force component on the wiper shaft, whereby the wiper shaft can be displaced in relation to the wiper bearing. This type of axial force component can be caused for example by a pedestrian impacting the wiper shafts of the motor vehicle during an accident. In this case, the wiper shafts recede and disappear within the body of the vehicle thereby reducing the risk of injury to the pedestrian. However, the embodiment shown there is expensive and cost-intensive and therefore only suitable in a limited way for reasonably priced motor vehicles. 
     SUMMARY OF THE INVENTION 
     The advantage of the windshield wiper device in accordance with the invention is that it makes a simple realization of pedestrian impact protection possible, which is also cost-effective and allows precise adjustment of the axial force component required for the wiper shaft to recede. This is achieved by a securing device that has a bushing section with an indentation, which engages in the undercut of the wiper shaft. 
     It is particularly advantageous if the undercut is embodied to be radially circumferential. As a result, the undercut can be made in a simple manner when machining the wiper shaft and a further processing step in manufacturing the undercut is spared. 
     The axial force component can be adjusted especially precisely via a tub-shaped embodiment of the undercut. 
     If the indentation in the bushing section of the securing device is embodied to be radially circumferential, the securing device can also be manufactured in a very simple manner and placed on the wiper shaft without having to consider the radial position. 
     In this case, it is especially advantageous if the indentation is embodied to be tub-shaped in cross section in order to carry out a precise adjustment of the required axial force component. 
     Ideally, a flange section that is effectively connected to the wiper bearing is attached to the bushing section. As a result, the axial force component acting in the case of a pedestrian impact can be optimally transmitted to the securing device since a large surface of the securing device is supported on the wiper bearing. 
     The wiper bearing can be protected from dirt and moisture by a bushing-shaped closure section, which is attached to the flange section, making it possible to dispense with an additional closure element for the wiper bearing. 
     Especially simple and cost-effective manufacturing of the securing device can be achieved by a structure of the securing device that is essentially rotationally symmetrical and essentially S-shaped in cross section. 
     It is especially advantageous if the rotationally symmetrical securing device has a radial gap. The securing device can bend open via this gap so that even small required force components can be realized. 
     The securing device can be embodied simply and cost-effectively as a punched bent part made of sheet metal. 
     In addition, the embodiment of the securing device of fiber reinforced plastic is especially advantageous. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       One exemplary embodiment of the invention is depicted in the drawings and explained in greater detail in the following description. 
       The drawings show: 
         FIG. 1  A schematic depiction of a windshield wiper device in accordance with the invention 
         FIG. 2  A partial sectional representation of a wiper bearing of a windshield wiper device in accordance with the invention 
         FIG. 3  A detail of an undercut in the wiper shaft with the securing device 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  shows a schematic representation of a windshield wiper device  10  in accordance with the invention. It is comprised essentially of a support tube  11  on which a wiper motor  12  is fastened. The support tube  11  has two ends on each of which a wiper bearing  14  is arranged. 
     The wiper bearing  14  is comprised essentially of a tubular section  15 , which is penetrated by a wiper shaft  16 . The wiper shaft  16  itself is connected in a rotationally secured manner at one end to a driving crank  18 , which is connected via a thrust rod (not shown for the sake of clarity) to an output crank  20  being driven by the wiper motor  12 . 
     In operation, the output crank  20  executes rotational or back-and-forth movement, whereby the driving crank  18  and therefore the wiper shaft  16  are put into a pendulum movement via the thrust rod. 
       FIG. 2  shows a partial sectional representation of the wiper bearing  14  with the wiper shaft  16 . The wiper bearing  14  is comprised essentially of the tubular section  15 , which is penetrated by the wiper shaft  16 . A fastening section  22  is arranged on the tubular section  15 , which is used to fasten the windshield wiper device  10  to the motor vehicle. 
     The fastening section  22  is essentially embodied as a flat plate, which is arranged essentially perpendicular to the axis formed by the wiper shaft. An opening  23  is provided in the plate of the fastening section  22 , and this opening is used to accommodate fastening means such as screws or rivets for example. The fastening section  22  is also provided with a circumferential side wall  24  for reinforcing purposes, which extends in a collar-like manner starting from the edge of the flat plate. 
     Arranged on the side of the tubular section  15  facing radially away from the fastening section  22  is a fastening connecting piece  26 , which has an essentially cylindrical form and extends to the outside approximately perpendicular to the axis formed by the wiper shaft  16 . This fastening connecting piece  26  is used to fastening the wiper bearing  14  to the support tube  11  and features corresponding fastening elements  28  for this purpose so that the fastening connecting piece  26  can be crimped with the support tube  11 . However, in a variation, the wiper bearing  14  can also be embodied as a one-part piece with the support tube  11 . 
     The wiper shaft  16  has two ends  30 ,  34 , which project from the tubular section of the wiper bearing  14 . On the first free end  30 , a cone and a thread are provided as holding elements  32 , on which a wiper arm (not shown here for reasons of clarity) can be fastened. The driving crank  18  is connected to the other end  34  of the wiper shaft  16  in a rotationally secured manner. This driving crank is comprised essentially of a longish crank plate  36 , which is connected on its one end to the wiper shaft  16  and bears a crank articulated bolt  38  on its other end, which is provided for connection to the thrust rod. 
     Sitting on the wiper shaft  16  is the securing device  40 , which essentially has three sections  42 ,  44 ,  46 , namely a bushing section  42 , to which a flange section  44  is attached, via which the wiper shaft  16  is supported axially on the tubular section  15  of the wiper bearing  14 . Attached in turn to this flange section  44  is a closure section  46 . The wiper shaft  16  and the securing device  40  are shown here in cross section. 
     The wiper shaft  16  has an undercut  48  near the tubular section  15 , which is embodied to be tub-shaped and radially circumferential. The securing device  40  correspondingly has an indentation  50  in its bushing section  42 , which is positively engaged with the undercut  48 . 
     The indentation  50  in the securing device  40  can already be provided during manufacturing and the securing device  40  can be slid with force on the wiper shaft  16  until the indentation  50  engages in the undercut  48 . In one variation, it is also possible to slide the securing device  40  without the indentation  50  on the wiper shaft  16  and then press the indentation  50  into the undercut  48  with an external effect of force. 
       FIG. 3  shows a detail of the indentation  50  of the securing device  40  and the undercut  48  of the wiper shaft  16 . The undercut  48  is embodied to be tub-shaped and as a result, has a base surface  52  and a side surface  54  inclined thereto by an angle of approximate 45°, and this side surface faces the free end  30  of the wiper shaft. An angle of 90° can also be provided on the side surface  54  facing away from the free end  30  since in the case of a pedestrian impact, the defined axial force component acts on the free end  30  so that the securing device  40  is pushed in the direction of the free end. Because of the inclination of the side surface  54  facing the free end  30 , the securing device  40  then glides on a slanted plane in the direction of the free end  30 . In a variation, the base surface  52 , for example, can also be dispensed with and a V-shaped undercut  48  can be provided. In another variation, this undercut  48  can also have diagonal side surface  54  facing the free end  30 , which side surface turns directly into the other side surface  54  facing away from the free end  30 , whereby a slant is provided for the side surface facing the free end  30  and an angle of 90° is provided for the side surface that faces away. 
     In a further variation, the undercut  48  is not embodied to be circumferential, but as a recess, whereby the indentation  50  of the securing device  40 , or more precisely of the bushing section  42  of the securing device  40 , is correspondingly embodied. In this case, only a quasi-punctual instead of a circumferential indention  50  is provided. 
     Of course, these possibilities can also be combined. In this case, although the undercut  48  would be embodied to be circumferential, the indentation  50  of the securing device  40  would be arranged only punctually however. 
     The wiper bearing  14  is manufactured as one-part with the tubular section  15 , the fastening section  22  and the fastening connecting piece  26  in a plastic injection molding process. 
     The securing device  40  is embodied as a simple punched bent part made of sheet metal. In one variation, this part can be manufactured, however, of plastic or fiber reinforced plastic or another material such as ceramic. 
     In operation, the flange section  44  is placed directly on the front side of the tubular section  15  facing the free end  30  of the wiper shaft  16 . One or more stop disks can be provided between the flange section  44  and the tubular section  15 . 
     The closure section  46  is formed to be bushing-like and grips over the end of the tubular section  15  of the wiper bearing  14  in a cover-like manner. Sealing elements can also be provided here in a supplementary manner to protect the wiper bearing  14  from penetrating water and dirt.

Technology Classification (CPC): 8